Finding suppliers is usually always the roadblock for anyone trying to start an e-commerce site or any other retail business. Often times it's hard to find anything at a reasonable price that can be sold to make a profit. It sounds like you are on the right path though, just keep doing your research. I'm not sure where you would look for a distributor or wholeseller for that kind of business but if you keep searching, you will figure it out.
The thing with blockbuster and walmart is that they do so much in sells that any distributor would bend over backwards to do business with them.