Lexus air shocks were about £900 each 3 years ago so probably more now. Arnott are the only aftermarket ones I know of but because they're made differently you would have to buy a pair. Lexus offered me a set of 4 genuine ones for £2,800 but again, that was some time ago. I see Rockauto do the Arnott ones for £445 each or FSC (don't know who they are) for £390. You've got tax and shipping on that. In the end you're probably better just to go to Lexus for everything, it'll give you peace of mind