http://www.usplastic.com/catalog/product.asp?catalog%5Fname=USPlastic&category%5Fname=72&product%5Fid=10369
1/4" HDPE...i ordered from here and they have extremely good service with very fast shipping....its a bit on the expensive side, but in my mind, it was worth the money...also, shipping is cheap (like $10.00) even though the HDPE is pretty heavy.