We have corrupted you
you have now felt the POWER....it calls you.. give in to it
The problem with the ebay HIDs is that I haven't found a way of differentiating them. I've bought them before and they seem to work 'just fine', no problems, and they all seem to be clones of one another. Alternatively you could buy high-end auto HIDs from namebrand manufacturers, and that would blow your budget sky high. For auxiliary lighting applications such as spotlights, where failure is unlikely to endanger life, I generally would not worry too much.
Some of them claim to be using namebrand components, however I have absolutely no way of verifying this so I would prefer not to treat their claims as definite.
You need to assess the risk for yourself and come to a decision, I can't do this for you. But I would consider a few factors (there are many more) such as the fact that incandescents can fail too (and do! bulbs blow), that if the HID fails it may only be one bulb at a time - you'll still have the other bulb and your high beam headlamps to get you home, etc. etc.
The kits have one ballast per bulb so a failure taking out BOTH at the same time would be exceptionally unlikely.
Generally I buy the bulb that fits my reflector. Start with the reflector for automotive lights, and it will state which bulb type it is optimized for. Then buy the HID bulb. If you mismatch them, chances are it won't fit, and the arc would be at the wrong height, resulting in very poor reflector performance. Each reflector has a 'point' where the light source must be inside it for max performance. This point is where the filament, or in your case, the arc, must be at.
The difference in the bulb types is really just a matter of making the bulb fit various kinds of reflector. Should be minimal to no difference.
