Here's what I'd do:
I run Ford/New Holland 5610 tractors. Can't be beat for the price and horsepower. Got both new for $10k cash each, traded in a 30 year old 5200 Ford row crop tractor on one and a 20 year old 6600 Ford all purpose on the other. 95 model is 68 horse, 99 model is 72 horse. I wouldn't want to bale with anything much smaller, but depends on where you are (hills, heavy hay?) and what size baler you want to run. 4020 is a good tractor, but anything in that 50-70 horse range would do, IF IT IS IN GOOD MECHANICAL CONDITION. Check the tractor over with a fine tooth comb-- BIG money to fix and real easy to hide stuff about to go out. Sure wouldn't buy one at auction unless I knew the guy who had it and what shape it was in or got it for an absolute steal, even then be careful because getting it for a steal means you'll probably spend the money on repairs and still have crap. Buy tractor from a good reputable dealer motivated to make a sale rather than BS and jerk you around trying to make a killing off the occassional sales he happens to make. Shop around, look at parts available locally but don't be afraid to buy that brand from a dealer a ways off if he'll make a better deal. I went to a dealer 100 miles away for my tractors because the local NH guy wanted $18k after trade versus $10k up the country.
Mower-- I've got a PZ Zweegers CM212 drum mower-- bought new in 89 and run it every year, cut roadsides and custom, only had to replace U-joint and yoke once. Rebuilt it last year with a new cluster gear $500 and new slides underneath for about $300. Works really good and only 6 gears in the gearcase. 7ft2in cut, wider would be nicer but consistently cut at 6 mph. Keep sharp blades, 8 total reversible so pretty cheap to run. Sure wouldn't want to go narrower than 7 foot though, and 9 would be better. Hard to find drum mowers anymore. I'm looking at upgrading to a Kuhn disc mower when I can afford to, as that's about what 90% of guys run here. Lotsa deals on used disk mowers but BE CAREFUL. Lotsa moving parts in disc mowers and most of em daisychain together. I check out mowers at the auction frequently and some are good some are dogs. Look for smooth turning bar (make several complete revolutions to make sure- no catching or hard spots and check that all disks turn in time, check the amount of backlash from one end of the bar to the other--disc on the far end should start turning within less than 1/4 turn of the other end, more than that pass it by) Grab the individual disks and rock back and forth forward and backward and up and down. Noticeable movement= bearings shot. Inspect the discs for cracks/excess wear- no loose bolts or egged out holes, especially in blade bolt holes. Look at the bar skid plates and noses for excess wear. New disks and skids=$$$. Look between the disks and bar for twine, wire, etc. Dust and dirt in there should tell you what kind of fields it's been run on--sand wears cutters out faster than clay. Check where the bar mounts to the frame. Bolts should be tight, not egged out and on machines with bushings, make sure they're intact and that the bosses aren't worn out or the mounts egged out from the bushing having gone out and run that way awhile. Check frames for welds/cracks/bends/warps. Check the driveline and overrun clutch, belts, pulleys, etc. Check the curtain and frame. Gotta have a curtain and don't want a busted frame letting it wave like a flag while you're cutting. You could go with a sicklebar but for the money you'd probably do better with a disk mower. Haybines are nice if you need the conditioning but check the rollers carefully, and the drives and wobble box, and cutter bar for proper operation and general condition.
Rake- I'd go with a rolabar rake myself because they're more versatile. You can be tempted to get a wheel rake because there are some dirt cheap but I'd think twice. Rolabar rakes can handle short hay, long hay, heavy hay, light hay, wet hay, dry hay, legumes, grasses, and just about anything else in between better than a wheel rake. Wheel rakes are ok on flat ground in medium yield hay with little wind, but I've seen them have all kinds of problems in windy conditions, with long hay and heavy hay like sorghum-sudan and johnsongrass, with any prairie hay with any stray vines in it, on hills, etc. I run a Kuhn cutter for a buddy of mine on occassion and he's constantly folding his wheel rake to dump a ball-up because of tough conditions. I run a NH256 and 258 on a double hookup and miss a lot less hay and do a lot better job with less loss than his wheel rake ever thought about. Irregular shaped meadows and obstacles in the field like trees and stuff to work around will definitely make you glad you have a rolabar rake too. Rolabars have more maintenance but definitely do a better job IMHO. You can find em pretty cheap at auction but watch for the following. Check the bearings on the bar ends first. Rotate the basket and make sure it turns smoothly and doesn't catch or hit any hard spots. Watch each bearing end individually as it turns to make sure it turns true and even with no slop or walking. Grab each bar end and pull back and forth up and down in and out. Shot bearings are readily apparent. Check where the bar bearings bolt to the end spider wheels. Look for egged out holes, broken holes, loose bolts, etc. Grab each bar and twist it to check for looseness. Shift it in gear and turn the basket. Forward it should freewheel, backward it should catch and hold with no 'ratcheting' or jumping (shot gearbox or ground drive dogs) Check the U-joints and ground drive ratchets. They should ratchet when turning forward but should hold when turning the basket backward. If you turn the basket backward more the wheels should try to pull the rake backwards. Listen for both ratchets clicking. Grab the wheels at the top and rock side to side, look for slop in the wheel hub bushings. Look at the basket suspension for broken parts, worn parts (especially the bellcranks which tend to wear sideways) and make sure the cranks turn properly. I bought my 258 with a lot of these problems, but I got it cheap and put all new bearings in bars, a new spider to replace egged out/ broken holes, new wheel hub bushings, new springs and ratchet dogs, and two new bellcranks for about $300. It's like a brand new rake for less than half the price. Rakes are easy to rebuild and the parts are reasonable, so don't be afraid of a 'dog' but make sure you can get parts for it (not a problem with NH but there are lots of others out there) and make sure the rake frame and basket/stripper bars are in good shape. If it looks like a D6 ran over it or it was folded around a tree it'll never run right, but if it's straight and not shot don't be afraid of a few bearings or bushings needing replaced, but price accordingly. Also, check out rakes on the dealer lots just as carefully as auction rakes. Anything you find wrong just drives the price down, unless they want to fix it for you before you buy.
Balers-- I'm looking at replacing my ancient Ford 552 (built by Gehl) one of these days. It's been a good baler but long in the tooth and parts are getting harder to find. It makes decent rolls but not the rock-hard beautiful bales these newer balers make. It's paid for so I'll run it til it dies I guess but I'm keeping my eyes open. I'm leaning toward Vermeer for a replacement simply because out of all the balers I've looked at, I like their design the best. They seem to have the heaviest bearings and shafts and chains. They just look "sturdier" and seem pretty simple compared to a lot of others, and I like simplicity and sturdiness. Don't want to start a paint war here but that's my impression. Course it depends on what kind of deal you can get and what shape it's in. Bout a million things to check on a baler, but generally speaking, check overall condition, focus on the bearings and rollers, condition of the belts, pickup and tines, chains and sprockets, hydraulic/air hoses/valves etc. rust, cracks, breaks, welds, look for burnt or ground out spots where bearings went out and ate up the side sheets, etc. I'd really want to make few rolls with a baler before I bought it. Baler is big $$$ and repairs are too, and if the rollers don't run true or if it's worn out it might not make a proper bale and it's too much $$$ to make a goof on this one. After all, even if you have a great mower, rake, and tractor, if your baler leaves you sitting your hay is going to be crappy if you get it up at all. Don't know if I'd be too quick to buy a baler at auction either, around here they're about as much at auction as you'd pay at a good dealer, and with the dealer you do have SOME recourse, though as the old adage says, you get what you pay for.
Good luck! OL JR