Buying a used CPAP machine can save a little money, but it is vital to consider the pros and cons before making this decision. Buying a used CPAP machine is only recommended if the device has been adequately maintained and serviced, which is rare. Otherwise, there are many safety or performance issues. There is mainly one advantage of purchasing a used machine, such as cost savings. However, this must be weighed against the potential risks of using an older model.