I get my hearing aids through the Veteran's Administration, since my hearing loss is service related. I have no idea what they cost, but I am sure that I'd have trouble paying for them if I had to buy them: I signed into the VA system when I could no longer afford ones that were powerful enough. The backups I was using were the old ones; two different types that cost around $300 and $900 at the time, about 18-20 years ago(!).
Hearing aids are not simply 'flat' amplifiers that ramp up the sound at all frequencies. Even the old analog ones I had were 'tuned' to enhance certain pitches. The modern digital ones are actually computers that are programmed to boost things in the way that will help you the most. They are also usually physically custom fitted to your ears. To get what you need you have to go through the whole process of being tested to determine your particular requirements, having an ear mold taken to get the right fit, and when the aids come in, they have to be tuned up to suit by an audiologist. Most of the modern ones can support several different programs for various circumstances. 'Speech' programs have a certain amount of noise cancellation built in, for example. When you're playing your guitar this will assume that the sustained tone of the strings is 'noise' and try to cancel it out. Speech programs also tend to boost signals in the 2-4 kHz range, which is where a lot of consonant recognition happens, which can contribute to a 'harsh' sound. I have a separate 'music' program I can select, which greatly improves instrumental music, but can work against understanding words in vocal music. There are 'phone' settings, and some aids will selectively boost the voice of a person you are facing, making it easier to carry on conversations in a crowded room. Many are 'Bluetooth' enabled, or can link in with other external devices, so that, for example, you're spouse can set the volume of the TV to a level they find comfortable, and you can hear it too.
Hearing aids are, almost by definition, an extreme measure. You only resort to them when you have to. They thus tend to be 'extreme'. You would not judge the utility of eye glasses based on trying a pair of 'bottle bottoms' that your friend needs in order to walk across the room without bumping into stuff. There are over the counter (or, back of the magazine) aids that are simple amplifiers, akin in many ways to the reading glasses you can get at the drug store (but more expensive, of course): good enough to be helpful for some folks, I guess, but not in the class of things I'm using.
Glasses differ in another way. For the most part they are used to correct focus: a good pair of glasses can get you pretty well back to the sort of vision you had (or should have had) when you were younger. With hearing, once you've lost acuity at a particular frequency, it's generally gone, and there's no way short of cochlear implant technology to get it back. Most people tend to lose the high frequencies first, and this is one reason why your friend's aids sounded so harsh: they were boosting that range to take advantage of whatever acuity was left to assist in speech recognition. The best hearing aid in the world is no substitute for the hearing you were born with. Do everything you can to preserve it.