I keep a colony of them, which is quite easy. (Ask if you want info how I keep mine) I originally got mine from varied sources, like http://www.lindasgonebuggie.com/ I’ve seen recently that PetSupermarket has been carrying them, but they are all super tiny and expensive.
I’ve had my discoids for about 4 years now and have no problems. Some have escaped at various times when I dropped them and I have no infestation. I have more issues with the wild palmetto bugs than from any roaches or bugs I’ve kept.