Try craigslist.com - its free for all and works well. I sold my old car in a heartbeat. You need to use multiple e-mails to register the add when you try to post same add in different states.
I sold my Harley through cycletrader awhile back, had a night train, sold in about 2 weeks, also for the one flat price as long as you remember to renew it each month it runs till sold!!!