My driver side head light has condensation inside of it? on 2007 Lexus RX400h

I took it to the dealer here and they said I need to replace the whole headlight assembly. Which cost over $800.00. There should be a way to replace the seal, instead of replacing the headlight assembly.

Asked by for the 2007 Lexus RX400h
I know, this is a common problem with a lot of new cars (not just Lexus) there are cheaper aftermarket lamps made in Taiwan but they are not near the same quality.Along with water entering the lamps the plastic head light cover's fade, old fashion glass was seen to be too heavy in weight no coincidence that plastic is cheaper.