Some models are made just for certain retailers. You'll find these to only be at Costco and others only at Walmart. It's been discussed why so I'll pause here.
I'm interested in buying this tv but it's hard to find a retailer that sells it. Has it been discontinued and has the UN65J6200AFXA taken it's place? What's the difference between the two?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic