I'm not an "OEM or nothing" kind of guy, and I love to save money. But at some point how cheap is too cheap? These are your headlights, not a cigarette lighter. If it was me, I'd be worried about quality, not just price.
Moisture getting into the assembly and fogging it up is a well known problem. BavAuto sells a repair kit, as do many others I'm sure.
If you have to replace, shop around for the best OEM price, don't just go by your local dealer. I got my M-tech bumper kit from Pacific BMW. BMWparts.com (Tischer BMW) also sometimes has good prices.
Just my two cents.
Interlagos Blue 06 M3
, Autologic tune, K&N CAI, Agency Power midpipes and exhaust, Fortune Auto coilovers, ///M
Pedal Kit, UUC SSK. MRegistry listing here
Le Mans 2002 M5
, Black/Titanium, Rogue SSK, Dinan exhaust, PSS9 coilovers, Euro rotors, iPod integration. MRegistry listing here