Just what to do with an old or used hearing aid is a question which arises for lots of people. You might have just replaced your old one with a better unit, you could have gotten a cochlear implant and thus don’t need yours any more, or it could have belonged to a relative who no longer needs it.
If the hearing aid was yours, the first option to consider it to keep it as a back up or a spare. If you lose or damage your new hearing aid and are without it for a period of time, you can revert back to your old one temporarily. 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.
You could consider selling the hearing aid on Craig’s List or eBay, especially if it was originally expensive and it is still in good working order. But first, make sure it is legal to sell used hearing aids in your state. Not all of them allow it. If you decide to try to sell it, be sure to list in your ad all the relevant information a buyer would want to know: the manufacturer and model number, the unit’s age and condition, warranty type, the type of battery it takes, and your reason for 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.
However, one option that is available to you if you can afford it is to not sell or keep the hearing aid but to give it away to someone who is in need of one. 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. U.S. organizations that collect hearing aids and give them to people who need them include HARP Program by Lions Clubs International, Hear Now by the Starkey Foundation, and SHARP (Sertoma Hearing Aids Recycling Program). Worldwide Hearing is an international organization that specializes in distributing used hearing aids in developing countries.