Visit the "Buy, Sell, Trade" section here and view the "Forum Rules" page. Also look at
http://www.bikeforums.net/showthread.php?t=44517 ; it references sites where you can post bikes, parts, accessories, etc. for sale. Post it at such a site, and then you can post a message in the "Buy, Sell, Trade" section here.
Also, of course, the're always eBay.