I am sure Wayne will chime in here soon, but he bought 3 box of 10,000 rivets for us but I can’t remember where he got them from. It was a good deal…that last 3 or 4 years worth of robots have been put together with those rivets.
We previously bought a bunch of rivets in 8000-pack boxes from BlindRivetSupply, but they no longer have these listed (only 100-packs…) and it looks like they were acquired by another company since last build season. :-/
I would not trust alibaba or ebay for anything structural in my experience. Electronics like power supplies or resistors are great. Rivets are a bad idea.