2007 HONDA ACCORD Parts - CurryAcuraParts4Less
You're looking for this - Number 7 on the diagram - It's $220 for just the LED cluster though.
IMO, it's probably cheaper for you to get new taillights from either ebay or a junkyard.
It doesn't really make sense that just 3 LED's will burn out though. They're SMD's if i remember correctly, and are imprinted on a circuit board.