I've been playing round on WeRipYouOffAnyCar site and sticking in the reg plates of some ISFs I know. One just came back with
Now I know this isn't accurate, but If cars are already being advertised at £13k, what are they going to be sold at..... £12K ish? So, a year down the line, £10k isn't going to be far off the mark.
Two cars on Autotrader at ~£14k are dealers. At least one has been up for sale for ages.
Cars are never worth what their owners think.