I accidentally ordered $200 worth of items through prime pantry, 95% non-perishables (including 24pk Monster, Solo cups, paper plates/bowls) to my home in the MidWest instead of where I was at on the West Coast.
2 minute phonecall, said keep everything and instantly refunded the entire order as a credit (my choice)
Luckily had somebody to bring everything inside back home too, haha.
Of course the day the replacement arrived, my wife pulled the old one out of the closet she had stashed it in.
I went to return the one I just bought and Amazon simply said to keep it and they would refund me because it wasn't worth shipping back to them.
Obviously won't work for everything and I imagine if I do that very often they won't let me anymore, but it's the best return experience I've ever had.