Thanks for the feedback. I did a test: I bought a used OEM assembly for the cracked lense for $60 and I bought a hella lens cover for the one that was oxidized for $18.
The BMW bodyshop in San Rafael preferred not to install lens only because he said you can compromise the seal. He cleaned the oxidation off with a solvent. No problem, only $18 dollars out for the lens.
The assembly was installed and I got out the door for $85 in labor and $78 in parts. The headlights look sooooo much better.