Panasonic do market their own, "self labeled."
I was not aware until reading this forum that LEXAR use Panasonic and SanDisk, and you don't know which you've got until the package is opened! YIKES!!
I would look for (obviously) Panasonic's own labeled merchandise and you'll be fine. That isn't meant to be condescending - you literally have to look for the name on the package or else you're right . . . it's a huge mystery til you read the back of the inside of the Card (and the package is opened!).
I got mine at "Fry's Electronics," either $69 or $79 around 3 months ago, but will have a look around and see if other retailers sell them; otherwise you can buy online from Fry's.
I remember looking and seeing that Staples, Office Max and Office Depot DID NOT carry them, but I'll check around.