5. Lawn and Patio Supplies (and Contractors)

Similarly, deck and patio furniture, along with grills and grilling equipment, are often deeply discounted at this time of year as people turn away from their yards and back indoors. For anyone planning ahead, though, that makes it the perfect time to buy. If you're buying wooden patio furniture, consult the National Wildlife Federation's annual sustainability scorecard, or shop at The Home Depot, Pottery Barn, Target and Jensen Leisure Furniture, which now stock only wood furniture certified by the Forest Stewardship Council for sustainability.

If you're investing in a new patio, porch or deck, now may be the best time to find a deal on a contractor, too, Yeager says – just be sure to ask for an "off-season discount." Same goes, at least during late summer and early fall, for home weatherization work, according to MacEahern – which makes things like insulation or a new storm door triply lucrative because of labor and materials discounts you can snag before the real cold weather hits, because of the energy you'll save on heating your home this winter – and because federal tax credits worth up to $500 for many projects are good only through December 31, 2011.