Nice set up... all you need is one or two more and you could breed your own and cut out the middle man. PVC pipe will work just make sure its wide enough for several to get in. Also go outside find some twigs for them to chew own.

I wouldn't worry about making hopper. In my short time span of breeding does seem like they waste alot via a hopper and bowls. You will notice that everyday you will have to fill it up. They dont eat that much. Best to just dump some on the substrate in a clean dry corner.