Where's a decent place for random robotics parts?

[deathproof]

Like chains, sprockets, etc?  

Maybe some sort of junk bin at a bike shop? Some towns also have "bike share" programs where they fix up bicycles to sell/rent/lend - same thing, they might have leftover parts.

I go on Govdeals sometimes to look for computers or vehicles and I was bidding on a lot of something like 40 bicycles a town was selling. Some of them were in great shape, in which case we probably could have fixed them up and sold them. The leftovers would have yielded plenty of sprockets and chains.

Unfortunately we got outbid, but I have a scrap guy who gives us a few bucks for old/dead computers every so often. He would have loved to have gotten a couple dozen bike frames for scrap metal.