Elie-chan Cat
would they have the original DS?
If they allow sellers, like at a flea market, there might be one. Never been to an E3 so not sure, but at the ComicCons they have a sellers room for "vintage" stuff sometimes.
edIT: emosgirl answered both of us on that, industry officials only - no sale room for vintage, oh well, check your local conventions tho, and Amazon or eBay, they sometime pop up there.