I would go to a ranch within a hundred or so miles from you that has cattle you like and a ranch that is accepted by folks around you (such that people purchase bulls from them)--usually they are fair and will treat you right I would purchase as many older cows as I could. Usually they have a calf or two left in them, and they have stood the test of time at the ranch that has already tested them for being good over time.
I haven't been in cattle that long, and I did make some mistakes.
1) I purchased older cows (but the seller wasn't so fair), and I ended up with lesser quality and loads of problems. Ask about longevity in the line, the ranch or the cows purchased. If they tend to die at 8 and you buy her at 7, you know what you might get.
2) I would not buy heifers since you can't control their calving ability, the bull they were bred to (promises don't always hold true), and in 300 acres, you probably will have a problem rounding up the heifers if they have problems. Heifers are also not always docile, and if they are not good, a problem calving with a crazy bovine isn't so fun.
3) I would prefer cows that were bred to AI bulls only because the calves will be potentially more saleable, but if you like the herd bull they are using, I would take those cows too.
4) Make sure that you get cows with udders that are good since you don't need to have udder issues, and without a good udder, they will struggle to raise a good calf without your help. Bad udders make for a poor replacement or poor bull prospect for sale.
5) Don't buy across the country. Fescue is hard on cattle, and if they tend to be hairy, then fescue isn't going to do them any good, and you might have a bunch of non-calvers and animals that are sold for meat if they can still walk. (A friend had cows that were put on fescue and lost their feet. Some died. Another person I know had a bull lose his male parts--came back without them--they fell off.)
6) If you have $300K to buy cows (150 x $2k each), I would probably not purchase all the animals from one place--probably can't. I would go to 3-4 ranches (or even up to 6) and purchase cows that were bred. I would let the sellers know I was purchasing cows from 3 places, and I would make sure I mentioned that the cows that work the best in "my environment" will be where I return to buy cows again. Prefer cows that are at least 6, that way you won't get their culls that are not working at 3 or 4.
7) I would also ask about whether they test for BVD and what the shot records are. I would contact the county Ag to find out what kind of diseases are in your area, and if any are problematic (BVD is one), then I'd ask the seller what he does to avoid this problem. I would also ask what other issues I might have to deal with when I talked to the Ag person. (We have Foothills Abortion here, and not knowing that at first, I had problems I couldn't explain. Cows need to be six months bred to be safe from aborting the first year.) (BVD live virus given within two weeks prior to exposure could abort your cows that were not exposed.)
8) Ask about purchasing a bull with them if you purchase them only a few weeks bred. A bull will likely clean up your cows that were missed, and you won't have opens. Opens eat your food for a year free (if you don't preg check them all), and you don't need that loss. Since you won't be able to pick up heifer that get bred, use only a low BW/low epd bull so you don't have pulling issues next year or the year after that when you keep your own heifers.
9) One thing I would watch is Docility. If this is your first time around with bovines, I would not purchase one that had a negative epd for docility (I try to stay above 8). Outrunning a cow in 300 acres is not easy. I would also ask the ranch if they have aggressive cows. (Nobody does, of course, but I would walk in the pasture and see how they act before purchase.)
10) Don't buy something you don't like the looks of. You might have to look at that animal for years.
Contact me privately, and I will give you some names of folks not far from you that would treat you right.
Good luck.
