One must realize that these are two creative pinball enthusiasts that invented PinSound, and they also have other full time careers. They are contributing significantly to the hobby, and my guess is they are having to license usage so there is an uplift to the pricing to cover that. It's not like they are making thousands of these things and people are lining up to buy them, so unit cost is of course high. You have to view this as a niche product, and is does require DIY and some technical aptitude to get it installed and working which is why the community is so important as it relates to creating orchestrations for the various pins.
I get it that price is significant to many, and that not everyone can afford one (especially if they want to install on multiple pins). Well, the same thing can be said for many things in life, and I'm sure we'd all like to live in mansions, drive exotic sports cars, fly in private jets, and only eat at the finest restaurants, and even though very few of us can afford such things the market still sets the price. Everyone has to make a personal evaluation whether or not there is a cost-benefit return to them and either buy it or don't. If you can find discounted units on the secondary market, then more power to you. It really doesn't take much aptitude to install one, and with a little tinkering with the sound tools you are off and running with your own custom orchestration, let alone simply download one that someone else has already created if available.
I get it, to each his own, and we wish that everything was cheap and/or free, but from my perspective the bros are providing a significant contribution to the hobby, doing it at a fair price, not getting rich off the deal (e.g. they still have to work full-time other jobs). They also take an active roll and attend multiple pin shows in the US and give discounts on merchandise when they come. It is my thread, so I don't mind stepping up on the soapbox now and then, but as always diverse opinions are welcome.