Just for another opinion on the Tracker;
I sold my circa 1994/6 Webley Tracker Camo Limited Edition .22 for £100 a few months ago on another airgun forum. It had no sights with it but was in good condition otherwise and worked fine. I could have sold it for a little more but was after a quick sale for a cash injection.
Ultimately it's only worth what someone's willing to pay but I'd say looking at the Tracker anywhere from £120-£160 tops would be in the right ball park. Also it depends massively on how it shoots still, whether or not it's giving good power, what the blueing is like on the action and general overall condition which is very hard to determine from pictures alone.