Coffee cup inserts -- need a source

They sell plastic coffee mugs all over, if you're willing to discard the outer shell. You could get one from most gas stations and break it apart, or I believe many large chain stores like Target have coffee cups you can "personalize" by unscrewing the top and slipping a photo in between the clear outer layer and the inner coffee-holding layer. I don't think they cost very much- say 2 or 3 bucks, acceptable for a one off, certainly.

Of course, if you want to make 200 of them, that might get a little expensive.