Consumer electronics and computers (advantage: mixed). Factory-refurbished electronics — including home appliances and computers — can be a good value, particularly if they come with a solid warranty. Use extra caution, though, when buying a used laptop computer, even if it has been reconditioned; as anyone who's ever owned a laptop knows, they take their fair share of unintended abuse. With consumer electronics, before you decide to buy used, you also need to comparison-shop for comparable new items (since new prices often drop as demand increases) and make sure the technology is not obsolete to the point of your being unable to find necessary accessories and supplies.
Clothing (advantage: mixed). For casual wear, clothes to work around the house in, and children's clothing, thrift stores and yard sales are hard to beat. You'll pay only about 10 cents or so on the dollar compared with buying the same items new. For dress and business clothing — particularly if your profession depends on looking sharp — buy new, or check out consignment shops, where apparel is generally more fashionable, higher quality and in better condition (which is all reflected in the prices they charge) than what you'll find at most thrift stores. One other tip: Shoes of all styles and varieties are often an incredible value at thrift stores and are frequently sold in virtually new condition.
Mattresses (advantage: new). Mattresses and bedding are among the few things that even my Miser Advisers recommend buying new rather than used. Obviously there are possible sanitation issues — real or imagined — and the true condition of a used mattress is hard to judge until you get it home and sleep on it for a few nights. If you want to save some money, buy the bed frame used, but "spring" for a new mattress and bedding. (By the way, many mattress resellers will now accept your old mattress for recycling.)
Tools (advantage: mixed). The general consensus of my Miser Advisers is that simple garden and hand tools can be a terrific value when you find them secondhand. But beware of used power tools — and even electrical household appliances like vacuum cleaners — because they've often been used hard, and their best days are behind them. Even if you plug something in before you buy it used and it works, check for wear and tear on the power cord: A frayed or cracked power cord can be a sign of how much a tool or other appliance has actually been used and how much life it might still have left in it.
Books (advantage: used). Even though my livelihood depends on writing and selling books, I'm the first to suggest that buying used books is the way to go unless, of course, you're really smart and borrow them from the public library instead. It's not just about saving money and trees: Building your library by treasure hunting at secondhand bookstores and rummage sales can be as enjoyable as reading itself. And websites such as PaperBackSwap.com, BookMooch.com and TitleTrader.com let you pick up used books without even paying for them, just so long as you have another book to swap in return. Yep, in most cases it doesn't make sense to buy a new book.... Just don't tell my publisher I said so.
Jeff Yeager is the author of The Ultimate Cheapskate's Road Map to True Riches and The Cheapskate Next Door. His website is www.UltimateCheapskate.com and you can friend him on Facebook at JeffYeagerUltimateCheapskate or follow him on Twitter.
Also of interest: 8 Places to find extra cash. »