Sounds like there's plenty of value to be extracted here! If only there were some kind of niche market where people could trade just these items, perhaps some kind of Magic: the Gathering Online Exchange.
Also worth noting, one of the largest players in this space is Star City Games. I wouldn't be surprised if they spent a few million dollars per year buying cards from consumers. That doesn't count the money spend purchasing new product from the manufacturer.
To be pedantic, MtGox doesn't actually stand for "`Magic the Gathering` online exchange" like mherdeg was suggesting, but rather for "`Magic the Gathering online` exchange". A subtle difference,perhaps, but MtGox was never intended for trading cards like these (Alpha Black Lotuses and suchlike). Rather, it was intended for trading MTGO cards.
In other words, not an online exchange for Magic: The Gathering cards, but rather an exchange for Magic: The Gathering Online cards.
I just checked to see if the domain name was available mtgox.com, but some weird fake money site is using it for what looks like a pyramid scheme.
Considering these pyramid schemes always come crashing down at some point, maybe we can grab the domain after them?