For the heck of it, I bought the blue tooth speaker kit below from AE for $6 delivered to the USA.
Two 1/2 way decent speakers, a bluetooth module with a micro processor and stereo amp, plexi case, and a led light show board.
My EE/IP attorney son-in-law and I spent some time trying to figure out how they could do that.
The bluetooth module is preassembled. The plexi case was made for something else; on the back panel there was a power switch cutout (included) (where I put the USB C connector) and a hole drilled for a power connector (where I put the USB A which was supplied). Although the front plexi panel has holes that align with the gratuitous light show board.
Still, a bluetooth module with IR, microprocessor and stereo amp, faceplate,remote and battery?? Fascinating and scary.
Who is organizing the component sources and production? Govt?? Kevin figures the production cost at $2 USD max. Then the shipping. Reminds me of the chiclet watches in the 1980s. I went to Canal St. to find the best prices for bulk. Case, module, battery, strap delivered to US $1 USD @ per 100 units.
The reason I added the extra power sources is that I could not understand why the microprocessor defaulted to a voice prompt and MP3 mode when the A port on the front panel was used but not when I provided 5v to pins 1 and 4.
Down the USB rabbit hole where I learned that pins 2 and 3 provide a 3 v data plus and data minus trigger. These signals are used differently by different devices which explained why some devices are not interchangeable.
This then led me to USB C (which I am trying to standardize on). Holy crap, what a nightmare; explains many cable mysteries to me. Not that I understand anything more than to forgo any but USB C 4.0/Thunderbolt 4 cables.