GenuineDealz.com has the lowest prices on marine wire and battery cables that I have found. They also do custom lengths, lugz and heat shrinking for $1 per fitting.
I like Bestboatwire.com for these types of things too. They can do custom cables in whatever color, size, and fitting you need. Good prices, fast shipping.
Bestboatwire.com and genuinedealz.com are owned by the same person, out of Georgia.