If you search on ebay for 35mm clear leader you'll find a couple of auctions right now (or keep searching over time, maybe a better deal will pop up.)
I have a pile of 100' rolls of Kodak SO-291 aka 2360 film, which in its current state is a weird translucent red. It's a "direct positive" film. You could simply fix and rinse it and have totally crystal clear film. This was cut down from a 2000 foot roll and had the occasional couple of foot length with massive scratches (came that way from Kodak!), so I gave up on using it as experimental still film because of that quality issue. If you're handling it in light as clear film you could more easily work around the scratched areas. I'd send you rolls for the cost of shipping. I can put 2 of them in a small flat rate box for whatever that is these days ($7-ish I think.) Or a whole bunch of them in a medium flat rate box. (If you're truly planning on using them just as film base I'd take them out of the bags and cans and keep those, just sending you the film on core.)
Duncan