I just ordered new carpet from MikesMontes.com ....he gets it from accmats.com which I've always heard is the best...
I asked what the shipping weight was, the one I ordered with rubber backing was 37 lbs & cost $200/shipped , I was told the one without the backing was only 17 lbs & cost $145/shipped... I know what you are saying about the capet being heavy, but I couldn't imagine carpet without backing at all, I would think you would feel every detail in the floor pan below? I will post something once I get my new carpet...