FWIW, I have a Shimano 7 speed wheel with Mavic CXP21 rim sitting in my apartment. It was a free wheel that I was going to use on the trainer...until I discovered the 7spd part. I want to be rid of this thing. I can not attest to the state of the cassette (b/c I never used it, and it has been sitting around for the past several years in my friend's apt--she also never used it. she was going to convert it to a fixed hub then didn't). I can say that it's not new, but it might be in useable condition.

If you want it, I will just give it to you for whatever cost shipping would be. I am thisclose to just abandoning it on the side of the road.