What are my options with 120 film?

I would LOOOVE to buy a diana f+, and I have the money to buy it. I don't, however, have enough for a 35mm back. So where can I buy/process 120 film. I live in the suburbs, about half an hour from Houston. I don't think my parents would be happy to drive me there just for some photos, so is there like a special option at walmart or cvs/walgreens? And where can I get 120 film?