We were in Morisons the other day and bought a climber (I forget what it's name was) they had for sale. My other half spied an empty plastic tray that the climbers had been in, so she put the climber in it, and when I got to the checkout (she had gone off to find some carrots at the last minute) the guy at the till asked if I wanted it, to which I replied "yes" of course. Seems that they don't mind cutting down on their waste, and are happy to give away things that they would otherwise throw away.