I recently made the experience that you still get amazing prices, if you sell at the right location. I live in London and when I look here on eBay or Gumtree (Craigslist equivalent) used Macs aren't worth much at all. In fact you can buy them in every second hand phone shop on the High Street. And if you want a new one, manifold Apple Stores are only a few tube stops away.
Because of this, I took my (pristine looking) 2011 MBA home to Austria (where I'm originally from) and looked up eBay listings there. A completely different world: While the Best Buy equivalents in the country have now been stocking a few Mac models for the past years, there are hardly any second hand phone stores or the likes, where you can pick them up for a bargain price. You can order from Apple online, but apart from a few Premium Apple Resellers that don't always stock the full range or the latest and greatest, there is no actual Apple Store. I put my 2011 MBA (4GB, 1.8 GHz i7) on eBay and even to my own surprise it sold within two hours for 970 to a lovely guy, who drove down all the way from Vienna (250 km) to pick it up. I bought it in 2011 for about 1300, so I'm ecstatic.
I made a similar experience in 2012 when I sold my 2009 15" MBP.
I'd suggest to anyone to really make sure to find the best market, eg if you live in the US, perhaps don't try to sell in New York City - I can imagine the market is as saturated there as it is in London. Instead, try to list it locally while you're visiting family/friends in a rural area with no easy access to second hand Macs.
Hope my experience helps someone!