Maybe I missed the rules while I was reading, not sure. My question is how often should the shop deck be shuffled? I've been shuffling it all the time, but I'm not sure that's right. If the party shops and draws 5 cards and buys nothing, should those cards still be on the bottom when they come back next time, so they don't draw any of them again, or does the deck get shuffled so they might get a repeat item or two?

The deck is shuffled before a new quest, after shopping.

Anytime you access the shop deck, you shuffle it. When you pull a treasure chest in the search deck you even shuffle it then before drawing the card.

Thank you, sirs.