Buy me!

This package is a store in itself. It contains a battery, a charging mechanism, and a computer. The computer is capable of holding and transferring digital currency. The package looks up physical locations it's likely to be sold at. It bids for transportation to the most likely-looking location. To buy the product a person transfers the requested amount of digital currency, from which the cost of manufacture plus margin is automatically deducted. If there's enough money left the package can bid to be returned to the store to be refilled. It can also offer bids to be recharged. There might be a kind of shop which only picks up these guys, charges them, collects the money, and puts them down in a collection yard to be recycled if they don't get picked up. Financial transactions of this sort are managed via traditional contracts (the package offers and accepts contracts) or that new digital currency which includes the contract in the currency.

Outside the scope of this idea is how to prevent theft but it may be that emergent behavior will include much higher bids for stores which would only sell physical security and a centralized place for access to customers to the packages.