Try swappa or android.net. You cant place anything for sale in Droid Fourms.
From the Guide Lines of Conduct
13.DO NOT advertise anything that costs money. Offering Items or Services to Trade, are not allowed. Anyone trying to use DroidForums.net to advertise any item for sale will be issued infractions and or banned, and their posts will be deleted. DroidForums is not Ebay or Craigslist