I cut a very small, maybe 1/4 of an inch, piece of a business card and drop it in the back of the neck pocket. Works just as well. I've been wearing hearing aids for about 15 years, so I can hear a difference.
I buy my speakers from StewMac because they have good prices and if you "subscribe" for a year you get free shipping to Australia. So I have saved a small fortune because of this. Same for tolex and grill cloth - if they have what you want. So while I agree that they can be expensive, especially for custom tools, they can also be great for other things.