Peanut butter cost $6.43 for 400g, compared to $2.29 for a 375g home-brand version.
Despite the higher prices, the range of ethically based products is slowly increasing in New Zealand and overseas, mainly because of shopper reaction to high-profile campaigns.
Fairtrade bananas now account for a quarter of British supermarket sales, and the Australian supermarket chain Coles is converting its egg and pork home brands to free range.
New Zealand supermarket operator Foodstuffs, which owns Pak'n Save and New World, said free-range eggs now made up 15 per cent of its sales and free-range pork was becoming more popular.
The chain's Auckland retail general manager, Rob Chemaly, said many customers were concerned about ethical issues such as sustainability and bought accordingly if they could afford it.
"However, in these tougher economic times, many consumers are watching their wallets and opting for items that provide the most value to them and families."
Progressive Enterprises, which owns Countdown supermarkets, said it had introduced a free-range chicken home brand a year ago that was growing steadily in popularity.
Food campaigner and former Green MP Sue Kedgley said people wanted to buy healthy, sustainable products, but did not have enough information.
She blamed the Government and the food industry for refusing to provide labels which clearly stated the ingredients and health implications, as Buy right, and pay 25 per cent extra well as how and where the food was produced.
"The fundamental point is whether a label is simply a marketing tool for manufacturers or do we consumers have a right to the information that we want to make an informed choice.
"They're constantly trying to conceal the information consumers want," Ms Kedgley said.
Australian marketing expert Professor Timothy Devinney, author of The Myth of the Ethical Consumer, disagreed, saying many people claimed they shopped according to ethical principles but these concerns seemed to vanish at the checkout.
He said extra information on labels would not help as most people were more interested in price and quality.
Food and Grocery Council chief executive Katherine Rich said there was a clear divide between people's good intentions and their buying.
