There's a very successful one run by a preschool near me in a village hall and they take 20% of all takings. I'm setting a similar one up (but for all types of items, not just children's) to benefit my village preschool (only 15%).
I'm happy to give you an outline of how we do it but I think part of the success of these events is the fact that a cut goes to a worthwhile cause as opposed to making a 'profit' for an individual.
Thank you so much for your response WingDefence. Yes the only reason to make a profit for us it so we can pass it on to our named Charity which is chosen by our best friend who lost his young brother very suddenly in August.
Any info would be gratefully received I have a little army here all really keen to help but would also like it to be a success!