there are a few people on there selling 'genuine' samsung cables.. it works fine but phone has lag when swiping the screen!
I see no lag when swiping the screen but I can tell you that the picture is not 100%(maybe because I got used with hdmi output). But even so.. the picture is not 100% clear.. I would give it a 50% mark. You can not use it to read .. so if you plan to use this tvout for presentations and stuf.. then buy the original one.. maybe that one has better quality. However if you just want to see how it work and just to own it.. than buy the cheap one.
I have been testing it on my tvtuner. It looks like poor quality was because of the tv tuner. I have just tested the cheap cable on my 32 inch LCD tv and the picture is greate. So buy the cheap one. Go to a local electronic shop and ask for a video audio cable with a jack and 3 rca connectors.