Well, I bought Earthbound from EB Games back in 2002 and at least on the outside, it looks legit (with the front indentation and quality label). Plays fine, too; the save battery is still working after all of these years.
But, now I'm a little concerned. I'm going to take it off the sale list until I can crack it open and take pictures of the inside, where hopefully somebody here can verify if it is for real. What kind of bit do I need to open the case?