It's supposed to be the cheaper alternative to clothes shopping but for many, op shopping is still not cheap enough.

New research conducted by Otago University asked young women what would encourage them to use more sustainable fashion options like op shopping.

The clothing industry is one of the biggest pollutants in the world.

Associate Professor of Marketing Lisa McNeill lead the research and told Mike Hosking the majority of people said prices were just too high for second hand clothing.

"The big problem is the disconnect between being able to buy something new and the prices in op-shops. The fact of the matter is, you can buy a new piece of clothing for less than the price of a cup of coffee now days."

The majority of respondents said there's much cheaper alternatives available from online shopping.

McNeill says it suggests that the shops may need a transformation to keep up with fast fashion.

"It's a really complex problem. People in opshops are volunteers, they don't necessarily have the skills people in a retail store have, or the time or indeed the money."

LISTEN TO LISA MCNEILL TALK WITH MIKE HOSKING ABOVE