BlackLotusGo.com is a Magic: the Gathering singles retailer that accepts bitcoin. With a steadily increasing inventory of cards, BlackLotusGo aims to provide a wide variety of cards to the bitcoin community for low prices.
BlackLotusGo is also the only Magic: the Gathering store in the world offering to pay out bitcoin for Magic cards. Make sure to check out the buylist:
Unlike many other vendors, BlackLotusGo supports bitcoin by NOT converting BTC received into USD. These funds are instead distributed to individuals who send in cards through the buylist.