Susan Edmunds of RNZ How can food products that travel into New Zealand from other countries end up being cheaper than those produced locally? It's a question some shoppers have been asking because United States butter from Burtfield's & Co is being sold at Pak'n Save supermarkets for $6.99 a block compared to $8.39 for the Pam's product. But it's not the only imported product that is available more cheaply than locally produced options. The cheapest frozen spinach this week, for example, was packed in Belgium from local and imported spinach. Frozen baby carrots were also imported. Simplicity chief economist Shamubeel Eaqub said imported butter had been cheaper than export prices for the past two years. "The main thing is the US has a record dairy herd. They've had some problems in terms of exporting to China because of the trade wars, they have a bit of a glut locally.…