Twin Cities Surpluse (http://www.twincitysurplus.com/
) used to have a program for people flying in -- you arrange with them via email to put everything you need in a big pile, then when you get in, you load it up, and go to the Playa. They will not buy it back, however. Email them and see if they still do this service for fliers in.
If you're going to be buying stuff in Reno, drop by Louise's pages at http://civilizedexplorer.pbworks.com/w/page/15934810/CivExReno
and browse there. She has lists of stores by type, stores by freeway exit, and where to recycle and dispose of garbage, among other things.
As to whether to rent a camper or a car, it's a judgment call. You'll need to clean up whatever you rent, and apparently many places don't like to rent to people going to Burning Man because the rental can never be properly cleaned. Check Louise's pages on rentals, as she links to some Burner-friendly places; there may be a premium for clean ups, though, so read the terms carefully.
It seems to me you'll spend less and have less disposable junk if you rent an RV. However, you need to watch those extra fees that BM may involve.