know where I can find these pendant backs? (item i want to epoxy)

Hi, I am looking for something I saw in a store called a pendant back. It is different than a glass frame charm. It is similar to a picture frame, but it has a back, a soldered jump ring, and no glass or enclosure. You paste what you want in the pendant back, then epoxy it.

Here's a link to what I DON'T want:

Here's a link to what I DO want: I want to make some to sell but can't pay retail for them and Fire Mountain Gems doesn't carry them or Artbeads either. Anyone know where I can buy these at a very reasonable (or wholesale) price? I've googled and googled and ebayed and everything I can think of. Your help is greatly appreciated! Meteor