When you want to get spur gears, bearings, bushings, chain, sprockets, ANYTHING:
You go here:
www.globalspec.com
You can compare costs, get quotes, and search dozens of suppliers for the exact product you need. You need to register, but it's well worth it.
There will shortly be a very comprehensive list of the best suppliers for the best products relating to FIRST sized components on
www.boilerinvasion.org.... expect it sometime after Christmas.
Matt