I will sell our old phones at contract renewal time via eBay.
The last phones I sold were 2 Motorola V3 Razr's with accessories: case, chargers and random additional accessories accumulated over their history with me.
Clear your phone
List as used with any visible imperfections noted
Pack in original box if you have it
Take and post multiple pictures
My 2 phones were advertised together as 'his n' hers' and sold in excess of $100. I always start them at 9.99
Good Luck!