Sell, sell, sell

Sell now before it devalues further. Not sure you would get much for the camera body, after all the MkIII has been overtaken ages ago.
If you are selling you can get a quote on line from MPB in Brighton. I have used them a few times. Other alternatives are Park Cameras (not generous with their offers usually), Sex (not bad) or London Camera Exchange (I used them a wee while back as they gave me the best deal of all on a trade-in).
Good luck