Buy an Australia supplied Skyline R31 I think, drive that a round for a few years insurance should be cheap and so should the car.
When you've got a job and saved all your hard earned cash you can either sell it and buy what ever or do a RB25det conversion.
At least this way if you bin the car it's relatively easy to get parts, you start clocking up insurance history, your gaining driving experience and your driving a Nissan.
Nothing stopping putting a sport zhast, pod, headers etc etc but it's a hell of a lot cheaper than getting a turbo'd car.
What's the point of having a car you can't or might not be able to afford to drive?
Good Luck