They are nice reasons mate, i too had that view as well for quite a while, infact a large number of people probably did. Especially if you've been around 5+ years as those cars just didnt exist way back when.
Times have changed though & this time around I've purchased a very well modded car, circuit ready - for nowhere near what it would cost starting from scratch. I'll have it hopefully in the next week or so
There are plenty of brilliantly modified cars here in Vic, from reputable workshops and most of them are regular's @ trackdays etc.
I would strongly suggest you go along to such events, most people have a price they would sell their car for - GTR or GTS-t.
(FYI a 300rwkw GTR will be faster than a GTS-t hands down simply dude to grip)
If you go with the attitude of "someone elses problem" i think that's silly. You'll have just as many problems (if not more) in the process of modifying your own.
Buying someone else's reliably running car, means they've gone through that and sorted it out in due course
What is your intended use for the car?
How old are you?
You also need to factor not only suspension, but brakes and tyres. I mean 18's & tyres alone will come in around 3k depending on what you decide
You'd mince probably 6-8k just in suspension/brakes/diff/clutch and that's without even anything relating to the engine bay which wouldn't see a cent out of 7-8k IMO.
Otherwise if you wanna pursue this plan - read Hamish's post above, he's listed the parts you'll need.