What will sell best at a charity auction?

Every week a Guardian Money reader submits a question, and it's up to you to help him or her out – a selection of the best answers will appear in next Saturday's paper. This week's question: I'm organising a charity auction fundraiser for our local school and would like to know what sells best? Do people like to buy days out or other "experiences"? Or do things such as cases of wine raise more money? All ideas gratefully received however outlandish.