: www.McMasterCarr.com
: They are wonderful to deal with. They will not show shipping charges are
: checkout but trust me they are totally reasonable.

: But I second Bill, If your doing this for the strongback, just use plywood
: scraps and save the money.

They're actually not far from me.

Since the cross brace and station snaps call for HDPE as well, I will probably need a small amount, unless plywood works for that as well. I'll try plywood first, and go for scrap HDPE if not.

To double check, because the prices at McMaster Carr seem very low, we're talking about 1/2" thick HDPE, right? It seems extremely reasonable, particularly if you don't need to ship it. Way under the $150/sheet I'd seen earlier.