I think part of the answer to your question is what are you going to do with the calves? If you are retaining heifers to build your herd you want some good, known genetics, especially on your early/foundation cows.

Starting out I had 6 put-together cows and split the 90 day rented bull cost of $600 with my neighbor. Genetics was a complete mystery, especially calving ease. So initial cost was about $50/calf but calves varied a lot. Retained heifers but were a motley group.

Purchased a $2000 bull the next year for 6 cows and 3 heifers. Kept him for 2 more years, total of 3 calf crops. Sold him for about $1500. Cost per calf is minimal. Main issue is do you have a place to keep him and a steer separated from ahead of your calving time until your bull-in date?

There are many advantages to choosing your own genetics with a good, registered bull from a good breeder. You can also keep your best bull calf a bull and use him to spread your best genetics between registered bulls.  My rule is to have no more than 50% of any one sire or dam in any calf, but 50% is ok if you start out with good trouble free genetics.