154 airships were built for the U.S. Navy between 1942 until 1945.
133 K-class blimps
10 L-class blimps
7 G-class blimps
4 M-class blimps
Many of the west coast WWII blimps were shipped deflated by rail to NAS Moffett Field for deployment. The last Moffet Field blimp was deflated in 1947. It's envelope could have be shipped anywhere.
The Piasecki Heli-Stat used a post war "N" class ZPG-2W envelope.
The last 2 east coast blimps, ZPG-3Ws, were decommissioned in 1962.
That is a lot of envelopes. I would think that they would not have much recycling value. It is surprising that there would be surviving envelopes 20-25 years old laying around, considering that rubber deteriorates rather quickly (even with the silver protective coating).
Considering that the size of a deflated envelope is about the size of a railroad flat car, I would think a survivor would not be easily misplaced.
Still, finding one may be a major coup... provided that it didn't crumble away.
By the way, I think one would be nuts to think an original envelope could be made airworthy again.
http://www.moffettfieldmuseum.org/photos/showimg.php?file=/Blimps/last_blimp.jpg