Source for GT2 stuff…I need a bunch of it. 
I’m not in a hurry, so alibaba is certainly an option, but do you have any recommendations for where to buy a dozen meters of belt, and 18 pulleys?
Get it from @Adafruit_Industries1 because they’re awesome and the more we buy from them, the more awesome things they can bring us
They don’t source 10mm bore gears.
Doh. Sorry. That wasn’t specified in your original post
Robotdigg has been great for me
Ask any of the sellers on Aliexpress - many of them can get in touch with the manufacturers (or are the manufacturers) and will get or make you the goods you want.
@Thomas_Sanladerer That’s what started my thought process. I asked for a quote on the belt and the response was ‘we can sell it to you, but you’ll pay a ton for shipping’
I asked if he sold pulleys too and got no response.
robotdigg
Looks like Robotdigg will be getting my business with the right mix of parts availability and price.
Do yourself a favor and order extras of everything.
SDP/SI has a larger variety than I’ve seen anywhere else, but it can be pricier.
Ditto for robotdigg. Just search for them on aliexpress.