With a budget of $10k, by the time you take out basic suspension + brake mods and a set of semi slicks you would be hard pushed to have $7k left. If you need cheap parts, upgrades, labour etc then you will have to buy an Aussie delivered car, not a jap import. You can't just run to your nearest wreckers for a new panel or other parts, everything on a jap import is either a special order through nissan or hunting it down on forums.
I think either an MX5 or mid 90's v8 Commodore would be most ideal for that budget. Strip it out completely, put a halfcage a new radiatior, upgrade the front brakes and enjoy yourself on the track.