macbook value

Hello everyone, I just upgraded my wife to a new MacBook Pro and have her computer available. I am trying to figure out a fair price. Here are the specs: 13" MacBook, Late 2009 2.26 GHz Intel Core 2 Duo NVIDIA GeForce 9400M 256 MB 4 GB 1067 MHz DDR3 Ram 500 GB HD Superdrive Computer is in...