I've had an ISF so have experience of one. Whilst a very good car, I do think the majority are over priced now, considering the present economic situation.
They are also getting on a bit now, and although relatively bullet proof, a problem now could be very expensive to rectify, especially as most are now out of extended warranty.
Which brings us to the RCF. If you don't need 4 doors, you get the next best thing.
Same performance, newer, more modern looking, and the massive benefit of the Relax warranty.
Excluding those as write offs, there are a few about at £25k, and a good choice below £30k.
I know what I'd go for.