Since I live in the Portland Oregon area, both Van's Aircraft and Pacific Avionics are only 1/2 hour drive from my house. They had everything I needed for wiring so I was fortunate to only buy small amounts at a time as needed and never had to wait for UPS deliveries. As was already said, the leftover wiring supplies and hardware have been extremely useful thru the years for repairs, small add-ons, etc. Almost always have what I need on hand. I also found single conductor, unshielded, in 20 and 18 gauge along with a good variety of crimp-on terminals, and a variety of shrink tube sizes to be applicable to most situations.