I've been looking for a couple of weeks for a source of 4' x 8' Coroplast near me (San Jose, CA) and have gotten quotes of typically $50 to as high as $154 for a single white sheet! (from FASTSIGNS in Sunnyvale, btw) So far, the best price I can find locally is TAP Plastics in San Jose for $20 in any color. I might be able to do better, but I think I've spent enough time looking, so off to TAP I go....