Customers were asked to return the products to the place of purchase with the appropriate packaging for a full refund.
Rather than let the butter be dumped in landfill, the dumpster divers dispatched it to anyone who wanted it, with a warning about the risk of eating the product.
"We have a very inefficient food production system that creates a lot of waste," said the dumpster diver.
"It's the sort of waste that would have horrified the [World War II] generation, and which now horrifies my generation - an environmentally conscious generation."
Dunedin resident Joan McDonald, 57, was delighted when she found one of the divers had put six packets of the product in her mailbox.
She said there was nothing wrong with it and she had already used one packet to bake a batch of biscuits, a cake, some muffins and some pineapple tarts.
"It costs $6 a pound. Throwing it away is waste of the worst kind. I had to stop baking because butter cost so much."
She was far from worried about where the butter came from, because it was being used solely for baking: "200C will kill anything it catches in a dumpster.
"I think we should be given a choice about having access to it. If you let us buy it, people will buy it."