I think if anything, this 2 key PCB should be overkill.
You're probably right, but it would be hard to find a place to mount the USB otherwise. Honestly, the whole concept is ridiculous, but I'm having some fun with it.
Anyway, all the parts to build one (PCB, usb, switches, resistors, caps, diodes, LEDs) cost me ~$8. It would go down in quantities of more than 1-at-a-time.
If you wanted to build a bluetooth one based on the lady ada's bluefruit, you'd probably just wire up the switches directly and go with a little two-switch plate in lieu of the PCB.