Could you provide source where they claim selling about $1 million worth of goods in bitcoin per day?
All I could find is they sell about $20-30K every day and that they "only" had a bit more than $1M in bitcoin transactions in two months.

http://techcrunch.com/2014/03/04/overstock-com-exceeds-1m-in-bitcoin-transactions-in-two-months/
http://www.geekwire.com/2014/overstock-ceo-20-30k-bitcoin-sales-every-day/