Forgeline monoblock GA1 style 18x10 @ ~US$1500 each
Braid Forged GT 18 x 10 @ US$1300
Rimstock 18 x 11 (same as V8SuperCars use) are AUD 600 each, but offset may be a problem and the centre bolt is large diameter (75mm)
Braid do a fixing kit - images here .... search for "mononut"
http://www.braid.es/wheels/products/...ments_p19.html