3. "New" Cars, Bikes and Boats

September is when automakers will be rolling out out the next (2011) model year cars, so it's among the best times to get a good deal on a new 2010 model year car, Yeager says. If you are in the market for a new car, buy one of the most fuel efficient models, and if you need a bigger car, consider an fuel-efficient SUV crossover.

Consumer Reports agrees that September is a great time to buy current year-model cars, if you're hunting for a deal: "You'll save money up front because dealers want to clear old inventory. New models almost always cost more than those they replace—even slightly tweaked models often get a price hike—and discounts are less likely."

"Perhaps more 'green,'" Yeager writes, "the same can be said for shopping for a new bicycle in the fall. Next years models are being released and stores are anxious to get rid of excess summer inventory."

If you're in the market for a kayak (like the Dagger Zydeco 9 Blem pictured here) or canoe, too, now's a good time for a deal on the last of this year's models, or this year's inventory, according to Bill Kennedy, owner of Kenco, a 28-year-old independent outdoor gear retailer outside Kingston, N.Y. "You can buy them at cost or below cost this time of year," he said. Interestingly, now's not a bad time to shop for a snowboard, snowshoes or cross-country skiis, if you don't mind buying this year's model before next year's hits the store in a month or two, Kennedy said.