I would say £8k for a nice one (but jaysport just sold his - for I would presume around £7k - so maybe less)
8-9k for a very very nice std one
it all dependes on the market at a given time.
but remember its still a cosworth - so still going to be mucho £££ to maintain and modify unless you buy a concours one.
I am always tempted when I see good ones for sale - but after selling a mint one for £7k 2 years ago and realising I would have to pay nearer 9-10k for a similar one now I personally am resisting as for the money you can get more modern and better cars hence I'm looking for a E39 M5.
they are iconic and I love them - I just dont love the prices they are commanding.