Where to buy convertible top window plastic?

So I have the opportunity to buy a 325i convertible very cheap, but the plastic rear window has completely deteriorated (amongst other issues). From the research I've done, most windows are made of 40 mil PVC based plastic. Recently some manufacturers have switched to a urethane based TPU plastic that's supposed to be more durable. I've found top places online that you can zip out the window and send it to them and they'll put in new plastic, but my mother is a seamstress and has industrial sewing machines, so I'm fairly confident I can do it myself much cheaper. So here's the problem, where do I buy the plastic?

I would talk to marine supply places.

I'm in a similar situation. I'm going to try the local fabric/crafts store. If that doesn't work, marine supply.

Do they have marine supply places in Indiana?

http://emiata.com/ClearWindow.asp

http://www.miata.net/products/body/emiata_window.html

There's a vendor and some install insight, but i'm sure you can get the raw plastic somewhere. have you tried mcmaster.com?

found this too, from another Miata.net thread. Seems to be alot of discussion of this on miata.net:

http://www.tapplastics.com/shop/product.php?pid=308&

I got mine from an RV dealer--the same plastic used in pop-up camper windows, I guess. It seemed to hold up ok. I did replace it a few months later with a brand new, glass window top. . .

I'll give another vote for a boat/rv canvas shop.

they would call it eisenglass though.

For those of you with vert tops you want to take care of, there's a cleaner called clear to sea that's made for the job and helps protect the plastic. Also remember 100%cotton only on to prevent scratches.