While using the updated modules.lua this will work.
Single Item:
shopModule:addBuyableItem({'magic lightwand'}, 2163, 400, 'magic lightwand')
Backpack of Potions:
shopModule:addBuyableItemContainer({'bp of health potion'}, 2000, 7618, 900, 1, 'backpack of health potions')
Backpack of...