hey dude
good to hear you thinking about it and not jumping in to it. im 18 and at tafe (doing my 1st year) i own an r33 skyline and currenetly working part time and not making that much money (lucky to make $200 a week) and its really hard to drive my skyline everday (i sold it to my dad a few weeks back and buying myself a cheaper car)
insruacen is the biggest cost if ur young full over is like $4100 at the age 17, and if u have been insuranced for 1 year is around $2300 a year. fuel is about $50 a week due to the fact if u run a turbo import u should uses BP 98 only (which is always $1 or higher a Litre)
then u got to put away money for serives (which are like every 5000km and about $100-$150) then u got the little things that happen out of the blue (like for example i was driving and blow my oil line to the turbo wouldnt really happen to a stock car but mine had been change etc and that cost me around $300 or so to fix)
Imports/Turbo cars are alot of money, im going to swap to an n/a r32 or s13 type car now and it should bring down the cost of fuel/ and daily cost by alot
also with importing a 15yr car (at the moment the law hasnt change but alot of people think it will soon)your looking at a max of $2000 for compliance, you could get an s13 or 180sx for under 6k-8k
check out www.j-spec.com.au/list and if u need anything else just ask im more than happy to help