Polished the headlights with 3M restoration kits. The 3M kit works great, but I think it's a stretch to do 2 lights with one kit. So I bought 2 kits, one for each headlight.
I tried to protect the lenses with Lamin-X clear film but I was unhappy with my DIY result. I am going to ask my detailer to install another set of them, hopefully better than I did.
Philips German-made 9012 and 9011 HIR bulbs, high and low beams, $73.00r
3M Headlight restoration kit, used one for each headlight, $14.99r each
Lamin-X clear film for Z3, $34.95r
Total cost of this mod = $137.93
Total investment in vehicle to date = $6454.99