I'm using some EPDM rubber pond liner for a really deep grow bed. It had a rubbery smell at first, but that faded. I think I remember hearing that whatever you end up using, it will end up getting coated in bio-slime, so maybe in the end it doesn't matter a whole lot. But it does matter to me, and I would definitely avoid using PVC or anything like that.
I am also using some ... hmm, I think it's reinforced polyethylene..
Yes. I got mine from these guys.
I highly recommend using that stuff.
But for additional grow tubs, I went to the hardware store and got some extra large mortar tubs. Judging by feel, some of the tubs are PVC and should therefore be avoided and some are polyethylene (same as rainwater barrels or big water storage tanks).