Are you talking ready made reeds or just latex period?
If you don't mind doing a little cutting, try surgical gloves or UNUSED condoms. Also, if you can find them, dental dams supposedly work very well. Ask your dentist for them. (Beware, if you try a search for dental dams on the internet, you're gonna get a lot trashy results. Apparently, gays, lesbians, and other weirdos have other uses for them.)
For the frames, callpurrfect.com has them.
I suggest that first you look in the homemade forum here before you go putting any money down. There's quite a bit of good info here if you will take the time to look for it.
I may have a source for you in a couple of days. Pioneer Enterprises carrys latex at about .09 cents apiece. Comes in thicknesses from condom to .005. they have the frames and tape also. Let me see if I can find the number. Hmmmm 717-938-9388 They DO NOT take credit cards so order early or you won't get it in time for T. season.
I get my supplies from this gentleman, latex, frames, and tape. Callpurrfect carries them also, but you will pay through the nose. I went in on some supplies with the guys from work, and for 25.00, I got enough to make a couple hundred calls. They run out of the latex pretty early, so I would give them a call.
Glad to see another Pennsylvanian on the board! I know exactly where Greencastle is, I work in the Chambersburg/Shippensburg area ocassionally. I live right off 81, close to Linglestown. The guy that sells the latex/ call frames is in Lewisberry. I can't wait until April 27th!! Good luck to you.