We have used laptopscreen.com for years now - they are fast-ship, easy to deal with, and we don't get questioned if they ship us a bad one.
However, we had an experience recently where we were replacing a touch screen, and the unit we bought produced an image just fine, but the touchscreen wouldn't work. They replaced it ok, but said "that model has about a 50% failure rate on the touchscreen working or not out of the box - so we'll only replace it once". Incredibly, the replacement they sent us was damaged in shipping - they replaced it again, but in the end we still didn't get a working touch screen. The part number was correct so I know they didn't ship us a non-touch unit. Of course, the customer said "I use that all the time!". Frustrating. Not to mention having to disassemble any laptop top plate more than once is a risk. Damn brittle plastic & glued on wifi antennas, etc. We didn't make any money on that one for sure, and although the customer accepted our explanation, they weren't exactly satisfied.