ebay man.. i used to work at best buy and we sold them for 100$ roughly and with my discount it came to 6. 13$ or maby try craigslist... dont buy in a store ull get ripped off
Amazon has good prices on cables; but one that long is pretty expensive (almost $300), I'd move the equipment closer to the TV and use a standard 12 or 15' cable which aren't very expensive.
It's in the bedroom. I just wanted to use the Samsung as PC display to try Boxee. The PC and tv are in opposite corners of the room. I need 30 feet to do that. Monoprice seems to be the people's choice.