There are two recent ebay auctions for Westin Kierland that are at $11,000 & $11,350 right now. One ended recently at $10,999. All are advertised as 81,000 Staroptions.
Vistana Villages...there was a thread recently about the prices. There was one I was watching recently that ended at $7,000 which surprises me, as others have gone as high as $9,450, and I know that someone was asking if $8,000 was a good price, too. A 67,100 unit ended at $5,000 recently.
These prices are the winning bids, but do not include closing costs and reimbursement of current year's fees (if 2007 occupancy). Add $1100 in fees to the $7,000 bid, for example.
But like DeniseM recommends, buy where you want to go.
Either that, or be flexible with when/where you go, and be happy in FL or AZ if you can't get Cancun.