If you're looking at some great deal online, I'd avoid it unless it's an authorized Panasonic dealer.
Where are you located, and where are you seeing this? The "PJ" will refer to a specific region of the world, and tat will matter for warranty purposes, etc.
I'm in NY. It's from Spec-Comm. Actually, I did buy it. I'm trying to figure out if I should keep it. They said it is a HVX200A, but the box says HVX200APJ.
APJ means that it was shipped direct from Japan but it is for USA distribution. The APJ is actually one of the ways you know you're getting a legit camera.
The "J" wasn't always at the end of the model number and it had to do with how Panasonic was distributing the camera internally to Panasonic. They would send the cameras from Japan to a warehouse here in the states, then send the camera to the dealer. This caused a delay in getting cameras out to dealers and I'm sure incurred a greater expense to Panasonic. To get cameras out to the dealers at a faster rate and to save some money, Panasonic started shipping cameras out to dealers directly from Japan but they needed a way to mark that distribution method on the box and they did so with a "J" at the end of the model number. The camera's sticker only says AG-HVX200AP because that is what it is. They just needed to put the "J" somewhere on the box.
Jan, This is how it was explained to me because I had the same question but you may know in more detail why the "J" is on the box.