So does this mean that I can’t sell diamonds to a player with /paymoney for less than $100? Also is there a cap for selling horses?
This is currently being discussed by staff. Refrain from posting until we reach a decision on the matter.
Just going to lock for the time being, until staff has had a chance to fully discuss. 
Yes, you can sell individually for those prices.
No cap for horses. Whatever you little heart desires for that one.