Each owner sets his/her own price and terms. My guess is between $12 - $16 and up - depending on the resort, when the reservation is made and difficulty of securing a reservation for the dates desired.
You might look at posts over on the Rent/Trade Forum to get an idea of what might have been charged last year. Since no one posts details of any transaction, we never really know if the "advertised" price/offer/want is filled as posted.