I started with 50 back in November and I just now have enough to start feeding every now and then. When you order I would think they would just throw in whatever they catch which would more than likely give you both sexes, but they might not all be sexually mature. I know that you can order a breeding pair from www.theroachguy.com which are mature and ready to breed.
Wait.
Are you talking about 10 breeding adults, or 10 roaches of various sizes?
I got 12 breeding adults right now, and 200 feeders.
I'll have to add to my feeders, though, for a while as I let my colony start and grow, but I don't mind.