Buying organic and fairtrade products may bring a warm glow to your heart, but the cold reality is that they cost more. Now an Oxford couple have hit on a novel way of easing the burden on the family budget - the School Ethical Supplies Initiative, or Sesi.

Sesi is run by Rina Melendez and Paul Godden, who buy in bulk, and then resell in small quantities at the school gate. Their mission is to trade ethically, improve people's diets - and boost school funds.

Ms Melendez, who lives in east Oxford, said: "It's much cheaper to buy in bulk, but there's a minimum order price of £250-£300 and most people can't afford the money, or haven't the kitchen storage space.

"We were part of a group which clubbed together to put in a shared order, and we thought it was such a good idea that we decided to start selling per unit."

Since many of their friends were fellow parents at SS Mary and John School in Hertford Street, east Oxford, they hit on the idea of handing over the goods at school pick-up time.

The wholesaler, Infinity, supplies a range of food and other household products, but no fresh fruit and vegetables. Fresh eggs will soon be added to the list of 1,500 products, which is circulated by e-mail.

The couple take orders each week, which customers pick up from one of several collection points. Alternatively, people living in east Oxford can pay a £2.50 delivery charge.

Ms Melendez said: "The SS Mary and John headteacher, Pat Murray, allows us to use an old shed, and we decided that since many of our customers heard about us via the school, they could nominate the school as a beneficiary, to receive a five per cent donation on their order. Mrs Murray liked the idea because it was a way of fundraising."

The scheme has already expanded, by word of mouth, to include the Comper Pre-School and the After-School Club, as well as staff at Peers School, who give a donation to the Parent Teachers' Association every three months.

The couple first met at a development project in Ms Melendez's native El Salvador, and environmental issues are close to their hearts.

"We are keen to promote the idea of refills," she said. "It's our unique selling point. People are resistant at first - they find it complicated. But once they see it, they are converted.

"There has been a great response. As well as saving people money, we are re-using all this plastic, which is good quality. Reducing packaging is one of our aims.

"We want to sell things like rice and lentils in paper bags to cut packaging - and it should be cheaper for the customer."

The School Ethical Supplies Initiative doubled its customer base last year when it started to run stalls at farmers' markets in east Oxford and Wolvercote.

Ms Melendez added: "Also, the people from the market - other stallholders who make humous or bread - order all their organic ingredients from us in bulk. Then they promote us, and promote the refill service."

It has so far proved difficult to get more schools involved, however.

"It's hard to get through to headteachers - they have so much else on their plate. We are hoping to get through the back door and do it through people we know who are parents, who might like to put a proposal to their PTA," said Ms Melendez.

However, the business has expanded into a seven-day-a-week job for Ms Melendez.

Both she and Mr Godden, who has a full-time job as finance officer for Cancer Research UK, are enthused by the way the idea has taken off.

"We run our own accounts, and then there is administration, taking orders, packing and shelving. We have been learning slowly, but it is incredibly satisfying. In two years time, it should be easier."

Future ideas include clubbing together with other market stallholders to offer home deliveries, improving the website, which at the moment is purely functional - and setting up a Saturday refill point on the Cowley Road, possibly at SS Mary and John Church.

"We want to capture the shoppers who go straight down the Cowley Road to Tesco, without stopping at the farmers' market,"

she said.