V-spec's are not gun metal grey only.
The other differences you covered are pretty much it... not a hug difference. I would be far more focused on finding a clean 32 GTR than looking for a v-spec. Also I dont think you can get a truely clean example for under $20k. When I was in japan a dead stock 32 gtr that was really clean was selling for over $35,000 and thats in japan. A really clean example is all you want in my opinion, and unfortunately a lot of the gtrs that ended up in Australia are the ones that noone in Japan wants as clearly there is still a market over there for clean 32's.
Be prepared to look at a lot of cars and look at them extremely closely! Best of luck!