There is many suppressor designs, and some are very simple, and some are a little more complex.
One issue is the market, it is small because the percentage of gun owners that go through the NFA process is limited.
This means many of the parts are made in a shop with direct labor, not mass produced by the thousands by a large machine.
The next hurdle is the $200 tax based minimum. If someone is going to pay $200 already, they probably want something decent. Paying $200 for a $20 piece of junk makes less sense than getting something decent.
They have $20-$50 suppressors in parts of Europe in a bargain bin. Grab one from a bucket on your way to check out. They are intended to be cheap, work decent, and be relatively disposable.
Of course the firearm is the heavily restricted component there, being as much hassle as NFA firearms are in the USA just to get many basic firearms.
There is also other concerns. The ATF has weird interpretations of what a silencer is. As a consumer you cannot just keep spare parts for your silencer, because those can be considered a silencer. If it breaks you cannot just order a baffle.
So what could be made really cheap should instead be made robust and relatively overbuilt and should have the ability to be opened, and readily cleaned. Instead of replacing cheap inexpensive parts when they wear out you should have heavier more resistant components that will wear slower to compensate for the law making it a hassle to replace parts.
If you are going to have all of that and related increased costs you might as well also have a design that works better than a cheap muffler.
You could mass produce a cheap version with wipes and an expansion chamber, but the minimum $200 tax, and required profit to make it worth the time of a SOT, already turns it into an item that is going to cost the consumer a few hundred dollars minimum, so it might as well be a quality robust item the customer will be delighted with for slightly more instead of stamping your company's name on a piece of junk.
While in places without all the legal restraints on silencers you can just make simple basic designs that are junk, but reduce the decibels effectively for awhile and price them cheap.
The same guy that invented the silencer also invented the muffler, being nearly the same thing just meant to attach to different devices. Another name for a muffler is a silencer, the UK for example calls all mufflers silencers.
One on automobiles is now mandatory in much of the world, including the USA. Instead of all drivers having to wear hearing protection due to the excessive noise generated by unmuffled engines, the vehicles themselves all have a silencer installed.
) Respectfully, there is a bit of design and precise machining that goes into one, and it isn't banged out in a matter of minutes (unless you are all set up with CNC, etc, and are pounding out a large number). If you are not precise enough, you get a bullet through your baffles, bad accuracy, a blown up suppressor, or all the above, and maybe worse (injury, etc). Throw in the liability associated with making one for someone else, and you get an idea of why they might be expensive. Don't forget, some designers and manufacturers really DO come up with great designs, and they want to make some money for the innovation and designing.
