Hi mate I paid around $1100 - $1200 for a set of 15" by 6" (one pair) and 15" by 7" (one pair) Superlite GTRs (lighter version) 12-18 months ago from Hornibrook Motorsport here in Brisbane.
I would expect the standard version to be somewhere around the $220 - $250 per wheel.
Best bet is to call your favourite tyre shop and ask for a price. Matty
While the car is a lot faster these days with the CA it no longer has the crisp turn in and mid corner adjustability that it did with the lighter motor. I tend to drive it more on the throttle than simply via steering input nowadays (I hope that makes sense).
I wouldn't say it handles worse these days but it isn't as much "fun". Fortunately I have also owned Bert's 1000 coupe for the last couple of years for that.