I agree people should be warned, but sometimes they won't listen
A while ago someone posted up (on here or another forum, I can't remember) all excited that he could get Bosch HIDs for very little money on eBay. I tried to tell him that there's no way they were Bosch, but he bought them anyway. I don't know how it turned out.
'If it sounds too good to be true, it probably is'. And if 'it' is on eBay then doubly so.
Here's the manufacturer's website...
http://www.boschhk.com/english/products.asp?classid=130
I bought my HIDs for about the same sort of money (I suspect that some of the more expensive kits are exactly the same product, so it's debatable that by paying more you'll get better quality), but I bought from a company that had it's own name, with no deceptive branding going on.