The 99-cent store. A conscientious consumer’s dream — and an insider’s cliche. (Who wants to troll crowded, dingy aisles to find a bargain?) How to live large on low expense? You just need to know where to look. That lost change jingling in your pocket can become anything. Like an airplane. (Well, kind of.) Who has time for airport check-in anyway? Get a key chain with an adorable airplane charm instead. Added bonus: It lights up. (Available at Tah-Poozie, 78A Seventh Avenue, between 15th and 16th Streets, 646-638-0750). Need some pampering? At Pearl River (a veritable buck-and-below bonanza), blotting papers only cost 75 cents. Then again, cucumber seeds are 99 cents — plant them, and cut slices for your eyes for your DIY facials. While you’re at it, throw some tomato and Chinese-leek seeds into the mix. Nothing is better for your health than homemade vegetable soup. Afraid to get your nails dirty? Pick up Chinese scented soap (in gardenia or milk). Not only does it smell good, but it also looks cool in the bathroom. Men can primp on the cheap, too. Toenail clippers — too few men realize how essential they are. (All available at Pearl River Mart, 277 Canal Street, at Broadway, 212- 431-4770.) Speaking of feet, it’s time to toss those sweaty summer flip-flops. Find your fall flips at R&R — in stripes and pastels that are cuter than the ones at the Gap. (Available at R&R Sales Corp, 139 West 14th Street, between Sixth and Seventh Avenues, 212-645-3094.) What’s better than penny candy? Cookies! Pocky Japanese candy sticks look like stirring straws, so they’re perfect for dunking in your anti-latte deli coffee. (Available at most New York delis.) It’s cold and rainy outside. ‘Tis the season for indoor fun. Rent any movie currently appearing on Pay Per View for 99 cents at Tower Records (1961 Broadway, at 66th Street, 212-799-2500). Don’t forget to jot down your movie list in the world’s most adorable notebooks. We couldn’t decide between the duckie and the hologram, so — radical! — we got both. (Available at Spend Smart, 420 Lexington Avenue, at 44th Street, 212-599-7821.) Remember: A penny saved is a penny earned. But if you don’t dig cukes, planes, or flips, save your coins anyway. Who knows? In fifteen years, you just might have enough for a pair of socks at Barneys. This is it! The last day of our exclusive preview of Donna Tartt’s The Little Friend, which hits stores next week. Missed a few installments? Print them out for some weekend reading.