Where to sell Nexus 7

Hi, I'm thinking about selling my "old" Nexus 7 16gb and getting the new one but I was wondering where I should sell it and how much it would sell for. I'm thinking about doing it on ebay but I have never sold any device and I was wondering how much money I could get out of it. All comments and suggestions are welcome. Thanks!

Oh, and I'm from the UK if that helps.