Hey! $15. per pair per month---the person searching for breeding is lookiong for a FREEBIE! No way for that price!
Think the going rate (more or less) for an "average" good bull is about $150 a month rent. I also wouldn't "room and board" any females for less than $3 to $4 per day while on my property. If, for example, his/her cows were kept for 2 cycles (5-6 weeks), at the daily rate...well you get the picture. A good bull 2+ years old should be able to breed 15 to 20 females easily. If he owner brought several females to your place to be serviced by your bull, could make him/her a package deal.
Also, consider your insurance, liability, etc., in addition to feed & care of animals brought to your place. And, ALL females brought should have all vaccinations and de-worming current BEFORE arriving at your place; and, they should be penned in an "isolation" area away from your other animals for health and other reasons.
Hope this helps!