I can't see why. You can get an ATMEL microcontroller at least as powerful (or more) than that one for $3 to $7 (depending on how capable you want it to be) in small quantities (qty 10). That's the SAM D21 CPUs ($3) and the SAM 3N or SAM 3S for $7.
I have to imagine the enclosure and such is more expensive than they thought.
The hardware seems pretty basic. I could make a prototype version from the CPU I just bought in a week. Yes, that includes sound triggering, opto triggering, etc.
Their AUX port seems HORRIBLY designed. They say it is powered, but you also can input signals? How? It's an RCA crown. It either can provide voltage and ground and look for a low resistance (short) across it, or it can receive voltages on it. If you really want to run active circuitry off it and receive a signal, you should use a 1/8" stereo jack and output power and ground and receive a signal in return. Then if you want to just use a short (like dry contacts) to trigger, you can ignore the power output, but if you want active circuitry you can do that too. Using the ADC to trigger is weird, even the $3 chip above has an analog comparator that interrupts you when a signal rises or falls and it can reference to things other than the 1.1V bandgap.
I just get the feeling they weren't nearly as good as they thought as what they are doing.