This is a pretty cute idea...but I prefer the freebies at expos than the stuff you gotta pay for xD
If there's no actual game aspect to this I'd think paying would be fairly pointless, since you don't really get anything out of it and doesn't seem like it's a lasting thing. I guess I'd think of buying as being more of a donation to a development company, or something.
I like how all the girls here are saying its cute XD. It might have freebies too, we don't know yet. From their press release, the item mall is to help fund the expo but I think it goes towards supporting the game companies too.