www.darvex.com (also sells on eBay under the username bag-boy and for that matter have a better look around http://www.eBay.com while you're wandering about the site)
I do not know if Best Buy carries 1/0awg cable or not as I have never inquired about it while in there....but I suppose they certainly might ~ though I'd be a bit scared of what their prices might be like...
I would have to imagine there are other good sources of cable that large and someone will likely be along soon to chime in with sources that I didn't think of.
i use welding supply wire. it does the job well for me.
i see you are from warren. back in the day i lived in warren //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
I just bought the kit from eD just because they give u soo many extra ring terminals,then i bought the fuse and fuseblock from Knukonceptz. Actually if u have the money u should get the Kolusus wire from Knukonecptz, those wires are outrageously packed well.