Best, OK, really good parts site: Mouser

No, not that kind of mouser, sugarbrie! WWW.Mouser.Com
Vishay, Nichicon, Xicon, knobs, switches, etc, etc, good prices, best of all no minimum order.
Kitch- Don't forget Michael Percy Audio for great parts.
No question Michael Percy and Welborne, too, for the more exotic and expensive stuff, but when you need a small assortment of metal film resistors and a few soldering terminals, the no minimum at Mouser is great. BTW, Audience,, has auricaps and very good service.
Yes, Michael Percy carries a lot of good stuff. Especially their capacitors and connectors. But, try to buy from Mouser WHENEVER you can. Prices are much less than audio leaning places charge. The only problem is that the selection for audio is dwarfed by the rest of their inventory. My personal favorite thing to buy their is Ohmite resistors. Best, cheapest speaker upgrade a person can make.