The Life You Can Save
There is almost no one who would not ignore their shoes and rescue the child. It's obvious to anyone in western society what is the morally correct choice in this case. Peter Singer devised this gedankexperiment to make a point. He wants to draw your attention to the moral equivalency of donating the cost of those shoes to effective charities that focus on children in the third world.
Children there are dying from preventable causes, as surely as the imaginary child in the pool. UNICEF reports that about 24,000 die every day from preventable causes related to poverty. Your donation of the cost of a nice pair of shoes would save lives.
Singer is a troublemaker. Philosophers are supposed to be aloof, he is not. He believes in activism. He's developed a website intended to help you find an effective charity for your donation and provide more information on the problem an his proposed solution.
He's not asking you to impoverish yourself. Instead he's suggesting that we can all forego some luxury if it means doing the equivalent of pulling the child from the pool.
You can hear an excellent interview with Singer here. Please give him a chance to convince you. He's got a very good argument.