As some may know, we run commercial and are probably no where as good a cattleman as some like
@Silver or
@Dave who deal in big numbers. Nor do we do registered. BUT, we do run 125-200 brood cows all according to the year, available pastures, etc... We spend on an average of 3-6,000 for a bull. HOWEVER, because we have many smaller pastures, we use alot of bulls.... and they can pretty well be moved wherever we need... and with pretty good records, I can keep them from breeding daughters or sisters since we raise many of our replacements. We do buy replacements too, with the cattle dealing we do, so we have a chance to be able to be pretty selective where we can put and use bulls.
Also, we keep bulls "forever"..... if they are not mean or aggressive.... if they do their job and breed the cows in a timely manner (passing a BSE) .... if they stay put and don't go wandering or fence jumping, they stay. Have 2 bulls bought in 2011 2012... 3 more bought before 2016. The 2 oldest ones are EASY CALVING bulls that we STILL use on heifers. They are about 1800 lbs or more, but are gentle easy calm breeders. Have never had either one ride down a heifer..... they throw nice small calves, 60-70 lbs probably.... heifers pop the calf out, it gets up, and goes to nursing and she is not hurting so is more likely to want to be a mother... I have a crippled cow that they have bred the last 2 years... she had a little limp when we bought her cheap, already bred. Was going to sell her after that first calf, she come up way along pregnant, so kept her. She stays in the "heifer pasture" and the bull catches her on the first heat I guess... and she just calved again. She raises a nice calf, and spends more time laying down than some of the others, but is no problem. But what I am getting at is that the bulls are easy breeders. Why not keep them. I can alternate them on the few daughters we may keep out of them so that they are not breeding back their direct daughter, sometimes a granddaughter.... we don't keep alot of heifers out of first calf heifers unless they are really outstanding; preferring to keep replacements out of well established cows with longevity in the herd.
We have lost a few pastures due to places being sold, and a few that the owners wanted to do something else or wanted way too much money. Gave up a couple with fences so bad that there was no "patching/repairing" the non- existent wire that breaks if you look at it.... that the owners would not allow replacement as part of the rent. Not worth the liability even with the insurance policy.....So we don't need any bulls for the immediate future.
I agree that 5 calves is a good base to figure the value or a bull. We have spent more a few times, and around here there are lots of bulls for 2500-3000 that I wouldn't want. So if we spend 3500-5000, it is not so bad since we plan to keep them a long time. Sure things happen, broken legs; or penis once, but your bull is 1/2 of the current calf crop and a good one is 2/3 of your replacements in value if he is a good one.