If you can't find anyone in the Market that has put their card up for sale, you could always place a bid instead. When you make a bid, card owners that are open to selling will be notified of your bid.
The OurCoin used to place your bid will be withheld from you account, and transferred to the seller if your bid is fulfilled. You will be able to withdraw your bid and get your OurCoin back, as long as the bid hasn't been fulfilled yet.