But I don't think, this is really a good use of BTC. Do you really want to pay for every item individually? Sounds like a lot of work even if it just scanning and pressing "send".
When I think, about it, there could be this box at the Exit, which can be unlocked by paying for it.
This wouldn't be a good idea either. If you're just picking up one of those "example items", then at the end someone else has to go around the store or the backroom storage to hunt down all your items. This is a lot of service required. Imagine the cost of hiring an army of employees to run around to gather items for the customer.
And you are not picking up example items, you just scan them, so they get prepared.