I reckon go the stocky....
Make sure it not too baddly damaged (scrathces) and go from there. Bash it round, mod it a little and learn from it. Then in a years time once your confident buy a GTR... LOL
Nah seriouslly i started out in a pair of R31 GTS-X's cause they were cheap... Didnt really matter if it hailed (well the first one i didnt care about and the second one was mint)...
I paid 8k for my second R31 GTS-X and traded it 3 years later for 10k.... So its all about treatment and mods.. I got money back on the car, mod money was the cost of driving it... LOL