Branded 'philanthropic recycling for the 21st century', www.buyoncegivetwice.co.uk, manages admin, and recruits donors, charities and buyers to the site for a ten per cent fee.
All profits will either go to the original charity or the charity of the new buyer's choice.
Bray Leino PR will target the charity sector and ethical buyers. The launch campaign will be a live auction in March, where celebrities and press will be invited to bid.
The site is the brainchild of Mia Woodford and Emma Leschallas. Woodford said: 'It is a stylish, exclusive bazaar of the lavish, the chic and on occasion, the downright strange.'
BuyOnceGiveTwice will offer a special prize of a four-day skiing trip to the World Cup Skiing Finals in Italy with Channel 4, to draw attention to the site.
The charity auction site goes live on 17 April.