a bigger electrical supply house will have much better prices on cable. I paid $115 for 50' of 8-3 SEOOW (600v, neoprene jacket). lowes and HD don't carry service cable that heavy around here, and I'd wager it'd be over $200 for the same cable if they did.

The two supply houses around here are summit and dealers. Summit is national, i think, but I don't know about dealers.