Here has been our experience: When we went to a bull sale and bought the bulls with the lowest birth weights, but fastest gain, we did pretty well. Unfortunately, those were the bulls everyone else wanted, and sometimes they ended up costing more than we could afford. This last time we had a budget for $3500. The bulls we wanted went for $4500. We don't have alternative income, so we ended up with some higher birthweight bulls having lower gain. But I will tell you that one of the best things we ever did when buying bulls was to go for bulls with a gentle temperament. Sometimes cheap bulls are also cranky. It is scary to be 50 miles from the nearest road, and have a cranky bull chase you. We just sold a bunch of bulls that a neighbor raised from his herd because they had low birthweights. We ended up with genetic deformities, and this cranky disposition. Generally you have less chance of genetic deformities with a registered animal. On the other hand, our oldest bull, Mikey, is one we raised and kept because he had a small birth weight and a sweet-as-can-be disposition. He has done well for us.