Idk about its value, but of course it's a rare thing. And I've noticed I also have an errata reverse palkia from GE, for it is only RH on like half the card!
So? Getting a RH Dialga (well, getting the right one) is hard. I've bought over 50 Platinum booster packs without getting one. D:
Maybe that's just me being unlucky again, but still. It's rare. It's valuable (well, to some, at least).