I have "ebay" headlights. I put quotes around them because I focused my search on Depo brand housings. I've had them since Nov of last year and I have 0 problems with them. No leaks, interior condensation, etc. They've been through rain, heat, cold, car washes, etc. There are some misconceptions in the responses in this thread.
1. Not all aftermarket headlamp housings are bad. I recommend anything made by Depo as it is a quality headlamp housing. Anything else with excessive LEDs, eyebrows, etc on eBay look really cheesy, IMO. Not sure who makes those either, so the quality may be questionable.
2. Once you get projector based headlamp housings, you really should consider an HID kit.
3. If I were to buy again, I'd get the Depo headlamp housings that have the UHP LED AE rings, like the ones seen
here. They have clear corners too, and most people want clear corners, I want to maintain the OEM look as much as possible.
4. There are vendors on this board that sell the Depo based housings, but only Bavarian X has the UHP LED AE rings.