Skylines and financial future should not be put in the same sentence together.
Seriously, if you want to have minimal car running costs buy a Toyota Corolla or Yaris/Echo.
If you want a quick weekend car that gets driven occasionally and not everyday then a turbo skyline is fine, more exp if GTR.
If you are a regular track goer and do want to push the car to the limits, then your wallet will take a big hit. Can you fork out a few grand if your engine goes capoot? What about changing tyres? you need to know that you have enough cash on the side for emergency situs.
If you want to buy a Skyline for around 14 K and thats all you have, but you also want to modify it and cane it, Id save up more dough before buying it.