After a festival with a lot of moisture, the lcd-blacklight broke down. But because I wasn't sure the lcd was the problem, I fixed it all.
I ordered the full 3GS Display assembly, it wasn't the first time for me fixing an iPhone. But still it was weird doing it on my own iPhone. After replacing the units I realized it was only the lcd so I switched the lcd's from their cases. Which means I've got my OEM glass, digitizer, earphone, etc.
First check what is wrong with the product. And if your not sure that there is only one problem. Repair some more things, better to much replacement parts than too little! ;)