Not the best price but a damn side quicker and easier than ebay
Review by confirmed purchaser
From posting (I printed out the label myself) to money in my account in 34 hours! OK - I got £150 and would have got more from an auction site, but this was much easier, and having bought a new phone outright I needed the cash back for the old one fairly quickly. Happy to recommend them, but if you want to maximise your cash and can stand the hassle, try eBay.