I've gotten a few quotes from local places, and places online.

Not only does shipping suck, but it's not cheap either. I think I found expanded PVC (5/8" thick) in a 4'x8' sheet for $170. When I sat down and started planning my cuts, I found that 4'x8' sheet didn't go as far as I'd hoped....even assuming no waste (and I'm probably not that good at cutting).

JonV