Buying anything used – whether car or Compaq – is a tried and true way of getting more for your money. In some ways, computers are an ideal used buy — they comprise mostly solid-state components that don't wear out, and companies that insist on state-of-the art equipment often quickly liquidate perfectly functional computers, funneling nearly new hardware into the used market, drastically discounted. Buy used but buy carefully with these caveats in mind: Used computers typically come with far shorter warranties than new ones; 30 days is typical. Some vendors offer optional extended warranties for an additional fee. Getting a batch of matching computers, which can reduce support, training and networking costs, may be harder to do when buying used. Your used computer may come with no online or telephone support. Consider how long you expect a computer to remain in service – a decision driven by how long a device is expected to last and by how effectively the computer's specs support newer operating system versions, applications or networks. A used computer that's effective for a year may not be cheaper in the long run than a new one that serves for two or three years. Find a local source When you buy your used computers locally, you're in a better position to test them and, if necessary, return them. For that comfort level, you may pay more than you would online. Shop online Not surprisingly, you'll find the widest array of used computer options online, not simply from sellers, but also from auction sites, recyclers and liquidators. As a rule, the lower the price, the more cautious you must be about the supplier. Look for refurbished PCs, overstocks and discontinued models Major PC manufacturers take their defective returns and former leases, repair them to factory specs and resell them, often from their Web sites. They guarantee that the PCs are as good as new but within a dramatically shortened warranty period. They also may sell off discontinued models at a discount, until they run out. Third-party refurbishing/overstock resellers do the same thing the manufacturers do, minus the assurance you may feel from buying from the original maker. Make sure it's a good deal How do you know that the price on a used computer is a good one for a computer of that age and specs? Always check the warranty and return policy Review the system requirements for your core software (Windows, Office, etc.) to make sure the computers you buy can do what you need them to do. When using auction sites, be sure to review the seller's feedback/rating. If replacing your old PCs with new, consider recycling or offering working computers to schools or nonprofits as a charitable contribution.