You'll find many used computers listed in the classified sections of computer magazines and newspapers. There are also used units for sale at various Internet locations. There are some excellent bargains in all of these sources, but buyer beware- know what you're buying. When you buy from an individual, you're taking more chances than if you buy from a dealer who backs up his sale. To Keep In Mind Try to find out if the unit that interests you has been used by a business or by an individual.
Individuals tend to use their equipment much less than businesses.
It's a good idea to run some kind of utility to check out the hard drive. Make sure the moving parts in the hard and floppy drive components are in good working order. This is not to suggest that some of the hardware won't wear out after you acquire the equipment. That can happen even when you buy new systems. Ask to look inside the computer.