Good morning. I am glad you posted this question here, as this is a topic that has not yet come up in this community that I am aware of. A good place to start is to call any of your local home healthcare equipment dealers. If you are unaware off such businesses in your area, you can do a Google search "Home medical equipment (your home town)" and businesses in your area should pop up. If they have a buy back program, you are all set. If not, then I am sure they can give you advice as to how/where to sell. While that is your best next step, another option you can try is online oxygen equipment sellers. If you Google "how to sell an portable oxygen concentrator" options will pop up. Please do let us know what you decide to do and what you learn. I will also investigate this at work today and see what I can learn for you. Good luck. John. community moderator.