Halloween costumes, tailgating supplies and floor-sample furniture
To pick up a great discount on a Halloween costume, shop online in September, says Hillary Mendelsohn, author of "thepurplebook" series of shopping guides and founder of ThePurpleBook.com.
Many online retailers "have specials that they'll run through the month of September that will go away in October," Mendelsohn says. "In October, it becomes a premium item."
Not only will you have your pick of costumes and sizes, but you'll be able to find markdowns of 10 percent to 20 percent, she says. After Labor Day, many online retailers offer free shipping.
Tailgating supplies are another category that's on sale this month.
With the start of football season, retailers are bringing out all kinds of merchandise related to tailgating (stadium cushions, coolers, team jerseys and the like), at special prices, says Daniel Butler, vice president of merchandising and retail operations for the National Retail Federation.
But if you'd rather pick up a few comfortable chairs and watch the game from home, you could still find a bargain. In September, furniture stores stocking new items may have a few floor models to clear. So you could find pieces for as much as half off, Butler says.