cpapauction has some good prices on machines. Often at savings of 50% off the price of a new Cpap at cpap.com. Obviously more savings are to be had if buying from your typical local high profit DME. A lot of times it's not a DME auctioning or selling the machine on Craig's list or cpauction.com. Sometimes, they do though.
If someone bought a machine from cpap.com and they auction it off, cpap.com is fair and reasonable enough to honour whatever remaining warranty is left on the machine. Nowhere does it say any other DME or CPAP supplier is obligated to honour a machine purchased from another DME. Imagine if car manufacturers say you can only fix your car at the dealership where you bought it? This medical industry seems to me, for a lack of a better word, is borderline corrupt.