For sale on the RD forum. I thought it was a bit expensive at £7250 until I read the spec and advert. http://priorygraphics.co.uk/aprilia-rs250/
Nice specs, but polished non-original frame will turn down a lot of potential buyers. Bling parts are easier to source than a nice frame with V5.
It has very good parts fitted to the engine and suspension, these should give more power and most importantly improve reliability. These are not visible so shoudn't impact the "standard" appereance. IMHO £7000 is way to expensive...but a tough one to judge as the seller spent probably 3k on upgrades...unfortunately fitted on a bike with scratched frame and questionable fairings....some decals are missing. See below how it should look like. 1998er Tetsuja Nero Diablo Replica, 7th picture down. http://www.aprilia-rs250.de/Modellhistorie.htm
Im currently restoring one the same model as the one advertised. Been stood in a coal shed for 15 years and as you can imagine it was manky! Also wish id never sold the one I had when I was 19!
good luck with the resto i done mine last year and parts can be very hard to locate but mine is a mk1 !!