I probably buy 1000-1200' of wire a year, and usually have 3500-4000'+ at any given time on hand - generally stock 12-14 colors 18-16-14 and 4 of 12-10.

For 20-22ga "signal" wire, I usually use Wire Barn. I order the 25' multi-color asst's on e-bay.

Del City has cheap small "put up" rolls whose roll lengths vary by wire size - usually 35' or smaller - works for most people doing occasional wiring. They also don't have line minimums for most items, so you can just order smaller quantities. Decent overall selection of electrical supplies, and decent pricing.

I buy most of my wire and supplies through Waytek Wire - probably the best prices for 100' rolls. I buy 100' rolls of GPT, unless a customer wants thinwall. They do offer custom striping, too. I buy the bulk of my supplies from them - switches, relays, Weatherpack connectors, breakers, etc., but they do have a $5 line minimum on most items. BIG selection of electrical stuff, tools, etc. You may save a few bucks shopping around, but Waytek has good prices and for most people is a 1 stop shop.

Hope this helps.