Just what to do with an old or used hearing aid is a question which arises for many people. You might have just replaced your old one with a newer model, you may have gotten a cochlear implant and thus have no need for yours any longer, or it could have belonged to a member of the family who no longer needs it.
One choice that does not occur to many people is to hang on to the old one so you can use it as a backup if something happens to your new aid or if it requires servicing. This idea has some merit, in the same way that keeping your old pair of glasses when you get a new pair is a smart idea, just in case the new pair gets lost or sat upon.
If the hearing aid was originally expensive and is in good working order, you can consider selling it on a forum such as eBay or Craig’s List. But first, make sure it is legal to sell used hearing aids in your state. Not all of them allow it. When creating your ad, list all of the information you would want to know if you were buying a used hearing aid: the model and manufacturer of the unit, its condition and age, whether it is still under warranty, and why you are selling it. Look at other ads from the past few months to help you set a price. Do not expect to get back what you paid for it.
An excellent alternate option is to give your used hearing aid to someone who needs it. Many people who need hearing aids cannot afford them, and there are organizations that collect old hearing aids and distribute them to people who need them. The following organizations operate in varies cities across the US collecting and redistributing hearing aids.
Another organization called Worldwide Hearing also collects used hearing aids for redistribution in developing nations where the people need them but cannot afford them.