German pilot’s shop Air Store has set up “a vending machine for spare parts” in Speyer airport":https://www.aerokurier.de/general-aviation/ersatzteil-automat-in-speyer/761144. From the picture it appears you can by engine oil, headsets, portable COM radios etc.
The manager of Air Store says: “The vending machine in Speyer is a first attempt by us of this completely new format. Even if it is commonplace in other markets, we are breaking completely new ground in the GA-market. Only by trying sometimes even partly crazy ideas, we can create new value for our customers of a kind that hasn’t been seen before.”
Vending machines in general are a licence to print money if you could have enough of them. The trouble is you’d want contracts signed in all the places you have them, and a hungry audience for the product. I used to have 6 vending machines in a factory, you could make 150% return on investment annually for about 6 hours work a week. If you scaled it up it would have been a good job.
Not sure about the margins on an ICOM, headsets, oil etc. It would seem to be alot slimmer margin than buying a can of diet coke for 35 cents and selling it for a 1 euro. It is like having a person standing behind a counter 24/7 for no wages so it could make some money if there was enough eyeballs looking at the products.
Does it stock KFC225 autopilot servos? You could do a roaring trade in those, at c. 3k a time…
PPL books, headsets and tom cruise glasses in a typical US flying school 
