One note of caution:
I would Google the company that actually does the trade in (EZTradin or Dealtree, it's listed at the top if you click through).
It's possible that once they get your item, they will either try and low ball you or say your item has no resale value.
Then they will probably say that if you want the item back, you have to pay return shipping costs.
I would also look at eBay because I think they sell stuff there.
If you've got a Craiglist.org city near you, it might be smarter / safer to sell there (just note there are a lot of international scammer fake buyers there, so definitely Google "Craigslist scams" before selling there).