Going by what I've heard from a relative who is an MD, the question is rather why low-quality hearing aids are expensive. The thing is, the average consumer doesn't know much about these things and how they are supposed to work. What the general sound quality should be. How long are they supposed to last etc. So you have loads of companies selling low-quality hearing aids at the same cost as the good quality ones. The consumers don't really know better because they are relying on the word of their doctors or consultants. Surprisingly, not many doctors know much about this industry either.