Re: Where to sell a timeshare?
First, do not use a broker. They typically charge an upfront fee on the order of $600-700, which you will never see again.
If they purchased the timeshare from a developer, they can expect to sell it for ~25% of their purchase price. For example, I own two weeks Florida oceanfront (2BR units) at a resort currently in developer sales with an asking price of $24,000 per week. I paid $4,000 for my first, and $2,700 for my second. A broker will be happy to tell you that they have clients waiting in the wings that will pay upwards of 75% of the purchase price. They lie. They will take your $600-700 upfront fee, and the deal will never happen.
If your friends have to bail out quickly, ebay is the best way to go. Place the ad such that the timing of the auction brackets 2 weekends, start the bidding at $1 with no reserve, and expect to get fair market value (~25% of developer pricing).
Redweek.com is another good option for selling. You can look at the ads on Redweek, and at the completed auctions on ebay to detrmine market value.
Do not waste your time looking at the asking prices on the plethora of resale sites on the internet. The asking prices are generally totally unrealistic, and will never sell.
If they can't bear the $$ loss on a recent purchase and want to learn to get the most out of their ownership, see tug.com (timeshare users group). Lots of good info there.