"But we can't afford to be supplying other retailers because we're already making a loss from this," he said.
Customer Paul Toeke visited The Good Food Trading Company about lunchtime and grabbed two bottles of milk. He said the milk special had specifically brought him into the store.
"You can't beat this. It's great because we love milk and it's expensive as."
He said there were three people in his household and they went through two and a half litres a day.
Meanwhile, sales at Nosh Food Market in Auckland had increased after the boutique grocery store dropped the price of milk on Tuesday morning to $1 a litre.
Chief executive Clinton Beuvink said he had an "amazing response" and real-time sales showed the store had sold "twenty times more milk" than normal.
He praised the actions of farmers and other retailers who offered cheaper milk.
"It's great to see more and more retailers getting on board with our milk price campaign - long may it continue," he said.
"We urge others to support the campaign because if you do get involved your customers will love you for it and support you - just as they have with us."
Federated Farmers chairman Willy Leferink supported the move and said attention needed to focus on supermarket margins.
with APN