Option 1: Listing Companies (poorest choice)
Historically, the most popular avenue for selling a timeshare is to hire a "listing company." Ironically, this is also the worst choice. These are web based advertising companies that charge anywhere from $300-$1,200 to list your timeshare for sale on their website. These companies only sell 1-3% of the timeshares they list. That means 98 of every 100 customers get nothing.
Listing companies often entice people to use their services by claiming they can sell their timeshare for tens of thousands of dollars. This is simply not true 99% of the time. Yet many sellers believe them and spend $500 hoping to make $20,000. They re-up after a year of no offers when the listing companies call to solicit another $500. The Florida Attorney General finally put a stop to this timeshare scam in that state and shut down most of the listing companies there in early 2010. See: http://myfloridalegal.com/lit_ec.nsf/ . However, many of the listing companies have simply moved across state lines and resumed business as usual.
If you plan on using a web based listing service, proceed with caution. First off, find a cheap one: www.thetimeshareworld.com offers free listings, www.redweek.com charges $75, and www.myresortnetwork.com charges $34.95. You also need to realize that most of the listings on these sites will be there for years without an offer. If you are interested in selling your timeshar before the next maintenance fee or special assessment, this is not a viable option.