RS500 for me also, I bought mine a year ago for around 20k I didnt buy as an investiment but as something to enjoy I have had it out to a few shows and it gets a fair bit of interest (actually gets more interest at non ford shows), then it goes home and is tucked up again for the next show. If I ever came to sell it I know I could get my money back, had a couple of offers over the year even had someone come round with cash trying to get it off me.

I agree with the above though, has to be 100% original and very low miles or I reckon it could be a bit more of a challenge to sell or make money on.