As I understand it, they're probably the same thing. I do NOT shop at GS or any other place like that, so I can't speak to the cases that they use specifically, but based on what I've heard folks here say, the cheap-o cases that I use are the same quality.
They get the job done and are dirt cheap. I tend to modify cases more often than not (doubles, triples, holding other types of games, etc.), and I'd way rather cut up aftermarket cases than OEM. Though, I am really bummed that those aren't even an option anymore
