How to time your purchases to save money

If you want to spend less on ketchup, stock up in May when it's on sale. It seems that for every purchase, even ketchup, there is a discount season.

Most people generally know they can get a deal by timing some purchases to a season -- to buy when demand is low or supply is high. Clothing is cheaper when it's "out of season" and certain fruits and vegetables are cheaper when they're "in season."

But the strategy is not so obvious with some items, such as ketchup. Condiments, including mustard and relish, are cheapest when the weather warms in May so supermarkets can lure you with visions of picnics and barbeques. "I know people who buy a year's worth of ketchup in May," said Mark Di Vincenzo, author of "Buy Ketchup in May and Fly at Noon: A Guide to the Best Time to Buy This, Do That and Go There."

Here are examples of how to time your purchases to save money: