"Copy/Paste store settings" - Its a big chore to make the same store in a different location. This feature would encourage businesses to branch out to different settlements.
"Adjust all prices by x%". - Convenient when you have 100 buy/sell orders and need to drop/raise prices across the board. Also removes the math when switching to a different currency.
"Bulk discount" - A way to automatically provide a discount when a player buys X amount of product
"Bundle" - discount when buying a variety of items. This could simply be putting a price tag on a shop category and buying the category means you buy everything included in it.
"Special Reservation" - Allows the shop owner to reserve items for a specific player. Particularly useful for large custom orders. This could also work as a new type of contract a player can create.
"Include ingredients" - When selecting items to put up for sale, you can tick a box that will automatically add the ingredients needed to craft it in the other section of the shop.