The BBC's offering up one of the current Doctor's outfits for charity sale. That's not something that happens often at all that often, and not shockingly, the bidding is rather brisk. It's part of the BBC's annual Children In Need effort -- which is why Matt Smith is hugging Pudsey The Bear (the Children in Need mascot) in the photo above.
It's the costume worn in "The Doctor's Wife" and "Night Terrors". The bow tie is included, because, after all, bow ties are cool. At the time of writing, bidding was at a sharp £820; I'd be stunned if it went that cheap.
Being the BBC, it's rather easy for them to provide a certificate of authenticity, although it should be noted that there's no guarantee that wearing this will convince Karen Gillan to come away in a blue police box with you; that would cost quite a lot more. [eBay via BBC Children In Need]