There are several types of tyvek - the kind builders use, the paper type that is used for Fedex mailing envelopes and another type that is much more like a fabric. The fabric type is available from sewing/quilting sources on the internet in small and large quantities. You can also get tyvek at the hardware store in the form of painters coveralls!
For all your subscription questions, go to the Book_Arts-L FAQ and Archive.
See http://www.philobiblon.com for full information