Joss has a section on the buy and sell part of this website.
It has average prices for all models of the Skyline second hand.
http://www.gtr.co.uk/BS.html
R34 V.spec '00 W, 29k, Black UK £37,000
R33 '97 R, 24k, White 400bhp £28,500 ... he'll be lucky!
R33 V.spec '97 30k, Purple 500bhp £25,500
R33 V.spec '96 P, 26k, White 360bhp £23,500
R33 V.spec '98, 39k, UK, 500bhp £22,000
R33 '98 S, 40k, Dark blue £21,500
R33 V.spec '96 N, 24k, Silver 380bhp £21,500
R33 V.spec '95 N 46k, Purple £20,500
R33 '97 R, 23k, White 380bhp £20,000
R33 V.spec '96 P, 10k, standard, Black £20,000
R33 '96 N, 49k, Silver 400bhp £18,500
R33 V.spec '96 N, 46k, 380bhp Silver £18,000
R33 V.spec '95 M, 15k, White £15,000
R32 '90, 73k, Black, 450bhp £12,000
-Elliot