Two hours looks about right for an average. While it's great that everyone gets paid (heh, wouldn't it be nice if that could scale to say... architectural comps or ad pitches), saying that $2.50 is a lot in some countries is just a bogus argument. So what if it is a lot of money to some people? Did you specifically seek out designers in developing countries? With graphics software, broadband, and 2 hours of free time to do little design jobs? That part seems sort of silly since the point of your post is that it cost virtually nothing
to you.
Now, I wasn't being sarcastic when I said that I'm glad you've satisfactorily solved your problem. Further, I'm glad that everyone you contacted got paid. But that doesn't address the problems which I see, which are that 1) it wasn't a very business or worker friendly (yes, in my opinion) move and 2) I think you could've done better.