For the sake of argument, I'll just figure out how much the Polycarbonate(Lexan) weighs.
I will also assuming that the polycarb cylinder is about 2 inches less then the total diameter of the wheel, which seems close based on the photo. I can't account for the weight of the hub insert or the weight of the metal rim it's self. If it's steel, it's going to be hefty.
Lexan has a density of .043 lb/in^3. Thats a little less then half that of aluminum (.098). The cylinders volume would be about 509 cubic inches. That yields a weight of roughly 22 pounds. Thats about what the stock 16 inch wheels on my Miata weigh, with a tire mounted.
I'm just guessing that the total weight of the rim is between 35 and 40 pounds, maybe more. Thats not something to brag about, but it is a lot lighter then many steel wheels of comparable size. But then, when has weight saving ever been a concern of an SUV?
They do look cool though. But eight thousand dollars? I've never owned a car that cost eight thousand dollars.