This is the final Idea I have for now, I think when you go to the bazaar, there should be a third row underneath the cards not in your deck, that are decked cards. When you try to sell one of those cards, it will say "This card is in your deck, are you sure you want to sell it" that way you dont accidentaly sell a decked card. Or if you dont want the decked cards to be able to be sold, at least have the third row so that you can see your deck so that you can keep better track of what your strategy is.