There is SO much important information you need about a bull that you can't see in an online auction....

I second Mark's idea of look up the name of some local (to you) breeders of the breed of bull you want (maybe through the breed association) and give them a call. Let them know what you are looking for and what's important to you and ask for their suggestions.

If you are breeding for club calves find a club calf breeder. If you are looking for a grass beef bull find someone with similar goals to yours.  And find a breeder with references and maybe call some folks who have done business with him. 

One bad cow or heifer means you have one bad calf.  One bull can be half of your herd and influence all of your calves next spring. Be careful in your choice of bulls especially. jmho.

Jim at Dawn