I have about 40 blue pearl in a 5 gallon. I started out with 6 about 3 or 4 months ago. They breed like rabbits, cherries and blue pearls both do. Dont let them breed together or you just get what the wild ones look like. Clear and nothing special. You will be fine putting them in a five gallon tank.
I've got a bunch up here in Dayton, ill meet you halfway at a dollar each, you know. Provided you want enough to pay for the gas. There's also a guy near the cinci Indiana border on gcas that goes by joedirt that was always selling them.