Best source for automotive wire

when doing any automotive wiring, whether it's a repair or modification, I've been using Marine Grade wiring exclusively now. Marine Grade wiring is fully tinned, slightly larger bundles with smaller individual strands making it more flexible and able to carry a higher load, and the insulation is rated for higher temps. Living on the coast I can walk into a bunch of shops and buy it but I'm sure you can buy it online easily. The downside is that you're limited to specific colors.