if you're looking for a little fun every now and then, just go to SAU's deca days. Not that hard on the car really (you can make it as easy on the car as you like if you really want), and only $70 i think?
Not that long a drive out to Shepparton, full day of having fun. That would probably satiate the track thirst.
In the mountains there are some great roads, i don't know about west, but there are some great roads there as well, some of the SAU vic cruises go out that way. You don't have to be stupid or break speed limits etc, just have a bit of fun with some spirited driving in some windy roads.
Great ocean rd has some very nice stretches as well.
So there are places you can take the car for a nice drive, but SAU Vic also offers some cheap track fun if you want as well.
If you're finding the price difference between the two aren't great, maybe just get the turbo, and then you can do whatever you want. Not to say you can't take the NA out, i guess you'd just have a bit more fun in the turbo