Here's a thread discussing a guy who refused an AA prize of 12 round-trip tickets that AA valued at a stunning $52,000:
http://www.flyertalk.com/forum/ameri...-declines.html
When you win a non-cash prize (car, motorcycle, house, etc) in a contest, in certain cases, the contest sponsors must collect 20% of the value from the winner and remit it to the IRS as withholding. That causes non-cash prizes to be turned down rather frequently, especially when the contest sponsor provides an alternate cash prize (which is always accepted).