In no particular order:
eBay for rare or specific parts I “need.” I’ve been burned a few times though, and prices are usually high. There are good deals if you’re persistent and quick.
I’ve bought entire bikes off Craigslist just for one or two parts. Just sell off the parts you don’t need. It’s convientient to pick up locally and actually see what you’re buying. The drawback is the higher initial investment of a whole bike and the time it takes to sell the unused parts.
Finally the C&V for sale forum here.
Good stuff doesn’t last long. It’s nice to deal with a friendly person who knows C&V bikes.