Thank you Wayne and John for those links. The challenge with places like this is that they have too much to choose from. I had hoped to choose common sizes, so that if there were to be a production run, the choices I make would be cost effective. Perhaps I should just let cost drive my decision on the prototype parts. A cheap gear is probably a commodity... hmm, or perhaps an odd size they are trying to get rid of! As I think more about it, to a toy maker who is going to make 100,000 of something, ALL sizes are commodity sizes.
Part of what took me down this road is that I became aware of how accessible rapid prototyping is nowadays. Some of the materials are strong enough to be functional as they are. Shapeways.com certainly has a nice web interface for their work, but I am sure there are a zillion other rapid prototyping service bureaus. The bottom line is that prototyping a plastic toy or robot is within anyone's reach. No need to do injection molding for a prototype.
Being unemployed (the 2nd time in as many years) is actually the main reason I am doing this. I have to design something!
Oh, by the way, the link for Stock Drives that you gave had an extra w. It should read,
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Joe Dunfee