This reminded me of a badass event of a similar nature at the airport. I forget what country I was in, but they had a similar return value for bringing back a luggage cart. I found an abandoned one on my way into the customs line, and was bringing it to the cart return for what I thought was maybe 0.25 euro, my wife being embarrassed that I would do this for "a few cents".
In front of me was an airport employee who had also had to gather up like 8 carts to bring back to the cart machine as well. He put his 8 in, with a whole euro popping into the coin return slot for each one, then looked at me with a smile and said he wasn't allowed to actually take the money (since he was already being paid to collect the carts I guess). So I jammed my cart in, and pick up 9 euro for my troubles! At the time worth like $15, and very much an awesome return on my 2 minutes of trouble.
I remember walking back to my wife jingling the 9 euro in her face, her in amazement. She's never said anything since about me grabbing stray carts, picking up change off the ground, looking in coinstars (find some silver coins every once in a while), etc.