I have a bunch of uretane coated rip-stop nylon. It is lightweight about 2.2 oz per yard. I think it makes a better ground sheet than tyvek or silnylon because if you put the urethane side up you don't slid around as much.
I will sell it to Whiteblaze Members, up to 20 yards at $.50 a yard plus $6 shipping (ex: 10 yards would be $11). I sell chunks on ebay with a low starting bid but it would be hard for you to find it at $.50 a yard. I only do PayPal on ebay but for WBers I will work with you.
I am not trying to make a quick buck here, just share a resource. No need to go to Ebay, just send me a PM through Whiteblaze or email me at [email protected]
ebay link:
http://cgi.ebay.com/ws/eBayISAPI.dll...0805&rd=1&rd=1