what are peoples favorite online stores to buy electronic parts?

im setting off on building my first self made midi controller and was browsing amazon for stuff, which turns out to be pretty limited. ive also looked into radio shack, and they have a better supply, but before i start ordering from 5 different stores i wanted to see if anyone knows of a good all in one store for the controller freak.

im looking for a place that would carry:

arduino boards and accessories
pots, faders, knobs etc and SANWA buttons!
a decent selection of plastic project boxes or enclosures

anyone know of such a place?
if not i guess ima go with radio shack, amazon and djtechtools store for buttons