Hey up Pez,
I would like to say rock on and buy it but that does seem very expensive, the way the market is at the mo you could get alot for 6 grand. I would try and knock him down some and buy it!! Dont part ex with him because you are been seen of with 1600 quid, he wont be interested with all that you have done to it, its just another scooby. Swap all the parts you want off yours on to the yellow one and then sell on your one on with not as high spec. Winner!