I own the R33 GTS. I love the car, but there are a couple things you need to be aware of.
65L tank means a full tank could set you back $87.1 (premium @ $1.34), but because you don't fill your tank when it's completely empty, a more realistic price is around $75.
A full tank of petrol can last you a week if you baby it, but I've personally budgeted for two refuels a week.
As a guide, for the past week I have been driving between 1500RPM and 3000RPM, never really hitting over 3000RPM and the fuel has lasted me a good week. I've gotten 500KM out of a tank once, but I drove out to Penrith and back two times in four days, and the petrol was gone at the end of it.
Third party, fire and theft cost me $600-or-so through JustCar, and was a one-off fee I paid for 12 months insurance.
If you can afford to pay for the car, then I would love to see another R33 owner (as long as you didn't ruin the car with tasteless mods). But if you're going by your wishlist without taking into account models etc. my friends ford falcon will smoke any stock R33 GTS and it's probably cost him around $6k all up? That's all well and good, but I love my car
You could also put $10k into a Hyundai Excel build, and that will give you a 900KG car with an Evo engine in it.
Smart cars are also really good. I dare say you would be checked for a turbo, so the 1.3L turbo could be good (not sure on how fast they are though). That's convertible too.
I drove an RX7 once, the older one, it had a full leather interior with the security code to start the ignition. Only problem is they are a lot of maintenance (so I hear). You can get nice ones under $10k, and they're really sporty beasts.
If you don't care about RWD, there are a few nice Hondas out there, like the prelude. The one with the triangular tail lights are prone to rust and other problems, but i hear the generation after it are quite reliable. They're putting a decent KWage out of it, also. Comparable to the GTS.
Iunno, it's your taste mate. I bought the GTS because I love skylines, and it was the best kept one I could find.