I sold my UK R33 GTR recently which was fairly standard with a few modifications carried out by Nissan Middlehurst running around 400BHP. I got £23500 for that which was a good price for the buyer. Looking at them now a decent R33 is £17000 plus. A series 3 R33 GTR will cost you around early 20s. All skylines are on the up, You could buy an R33 GTR a few years ago for £8000 thats what GTS-T's are fetching now. Its with many cars now for example the E46 M3 manual coupes, skylines, NSXs, S2000s and more. I think the Supra is part of that crowd as a around 6 years ago you could buy a TT 6 speed supra for £12000 which would be seen as a bargain in todays market.