Flower Arrangements

You can buy items from an NPC retail store as long as the items in the retail were set up to be up for sale. That said you may want to have a random household own it as once you buy an item from a retail it doesn't get restocked (well from my experience it never does) so you need the owner to go and restock the items or have the employees restock them for you when the store is opened (player controlled).

Edit: Curse you Auto correct