Sell? Sorry, I guess its been a while since I read up on the policies. I was under the impression that the MR route only required permits if you did an overnight trip. I avoided the permits for the main trail by doing the dayhike of the MR. Things must have changed. So, sorry, but I don't have any for sale.
Good luck
-Canuck
Permits are not transferable. You are correct that only overnight permits have an entry quota. Day hike permits are now required for North Fork/MR but they do not have a quota (and thus are not reservable).
As noted in the thread
Unused Whitney Permits, you should have a good chance of getting a cancellation.