well, there are some options
go to Ebay and search for BMW e34 foglights, there you see original Hella new or used, projector foglights made in China, or only the glass to DIY replace the glass, or DEPO foglights.

FCP has the foglight lenses for $51,95/piece for Hella, that is basically all you need. See page 2
BMW 535i Lighting Parts | FCP Euro

On my E36 M3 I replaced last year a original foglight lense with 1 from DEPO, so far no issues.