Try
http://www.supracarparts.com/ you can just email these guys with what part you need and they might have it or they might be able to get it for you if you ask them (maybe).
http://www.rockauto.com is another one; only if you need OEM parts.
*However do you have a targa top? If so fix any leaks before investing in new interior.
You should hit up a junk yard or a pick and pull. I found a nice n/a 87 supra that had way better interior than mine because it didn't have a targa top and now I use it for parts.