Yeah, just one male and one female usually does the trick. I hadn't had a pair for a while, so I go the itch for them again last year when I saw a stunning striped male at a LFS chain. He never did look that good looking when I got him home, ever. Must have been some funky lighting at the LFS. Anyway, I kept my eyes peeled for a nice looking female convict at different fish stores other than the chain I bought the male from to help insure the fact that the parents weren't related to each other. I found a decnt pink convict female while some black piebald markings, so I picked her up. Eventually She had babies with the striped male. I salvaged some babies from one of the spawnings, I moved the remaining 10 or so into a 55 with some cutteri fry. Sadly, the father got murdered, but I least I have some of his offspring to grow out.
You don't really need to find parents from different stores to get a good breeding pair, it's just something I did for fun on the side. As a matter of fact, I recently bought 4 marbled convicts from the same batch, they had such unusual markings I had a hard time picking males from females, so I just bought 4 and hope they pair off.
Good luck!