The Wedge Card scheme, which has been running in London since 2007, encourages local shopping through quirky rewards, as well as more traditional promotions.
"We've got one retailer who offers cardholders a free coffee every time it rains," said Wedge card founder Diana Bird. "An offer like that is guaranteed to stick in shoppers' minds much more than a normal money-off promotion would. It's all about making local shopping fun.
"We don't want people to shop locally because they feel sorry for independent retailers; we want them to shop locally because of the great products, quirky promotions and fantastic service that they offer," she added.
Bird hopes that the scheme, which already has 950 retail members in London, will be eagerly adopted by retailers and shoppers during the next stage of the rollout in Wales and Kent.
Retailers who join get a large window sticker and the chance to promote themselves in a quarterly newsletter and on the Wedge website. Shoppers pay £10 for a card.