Shopkeepers are one way transactionally, shops place items and customers buy item. In reality, shopkeepers can also make purchases.
Why not extend the behaviour to allow for what is found on the auction as “Orders”?
This can be surfaced in an Orders tab within the new “Shop Search”.
This promotes price discovery and economic activity.
Let Banks remain as “pawn shops”, it’s not encroaching on their functionality.
Heck if you really want to be ambitious, allow customers to send Offers to shop owners for items listed in shops and shopkeepers.