I am a fan of Waytekwire as was posted earlier.
http://www.waytekwire.com/prod...ive-Cross-Link-Wire/
Prices and quantity are affordable and easy to order but I would also point out it is a good quality cross-linked wire. The insulation is built for cars, durable and resistant to heat.
It is worth making sure you get wire designed for cars instead of generic spool.
As far as gauge, if you google it you will find a dozen web sites which give you gauge of wire and fuse requirements for most equipment.
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