OZ is renowned for making rally rims which are super strong.

Yup, those are excellent value for money. I almost bought Konig Hypergram for my Evo but they're out of stock.

Leggera series not too bad in terms of weight. Full forged rims like Ray's are even much more expensive right?

18' OZ about 7-8k.

I just use cheap rims, Racing Hart CP-S10 Face 2 (concave), size 18x9 +21, just MAT type rims.

The more popular the rims, the higher chance of getting fakes. Since you're very interested in that particular rims, I suggest you get to know every little details about it down to the minute markings, color and size variations,
weight, etc2 so that you can tell if fake or not. But generally the fakes will be sold at much cheaper prices, less than 2k for 18' size brand new.