start it on craiglist.org for your area. If you aren't getting any bites, buy a "run till it sells" ad on cycletrader. Don't worry about posting it on here. You're marketing to a crowd that potentially already has a bike, and the people here will be more stringent on price because they know the real value of the bike. People on craigslist might be more likely to take a higher-than-average price.