I'm getting a Model S Performance around October 2012 (I'm reservation #R270). I want the 19" wheels instead of the 21". Rather than just order the 19", I was thinking someone who wanted a 21" set (silver or gray performance) would get a better deal from me than the $3500 Tesla is charging. My understanding is that a second set of 19"ers will cost me another $1000.
So, if your Model S comes about when mine comes we can swap for $1925 ($1750 is half the savings, plus tax). If you want to buy them outright let's talk.
I'm in the SF Bay area. Local in person exchange/swaps are easiest, but I'll entertain any reasonable proposal.
PM me if you're interested.
EDIT: As of today (Mar2013) I do not have wheels to trade.