Not exactly loaded with info is it? I presume this is a Jet Stream Blues classic player 50s model?
When I saw the ad I checked what these have sold for recently over here. A couple of Daphne Blue Classic 50's have recently sold for 475-500 pounds, so 500 is about what they're going for it seems.$500 is the "buy it now" price.
Given that the current new price for Vinteras is $1,100 I think $500 is reasonable.