There is a guy in Des Moines, IA that sells some at a reasonable price. His name is Shooter aka Kris and Amy Nelson. I have purchased a few from him. He is very active regionally in Swap meets and auctions around the Iowa area and surrounding states. If you need his contact info, I can get it for you.
I also sugest Shooters fish room. If you want guaranteed males and femails you have to pay big bucks. If you buy little unsexed ones you have a better chance at getting what you want. If you buy unsexed adults you will probably get all males as it seems they spawn male heavy.