All depends on the timeframe. At this time, they are definitely "undervalued", primarily due to several factors like the economy and the arrival of the R35. Once you give it time, (it could be 5, 10, 15 or 20 or more years), I have absolutely no doubt it would appreciate in value.
Unfortunately this cant be said for "normal" R34 GT-R's such as your V-Spec, V-Spec II and vanilla specs purely for the fact that thousands were produced.