You can price it out at mouser, something in the $20 to $30 range. But the custom pcb really makes it easy.
paulb (of
Modern Device Company ) took some initiative early on and has some early versions of the board and plenty of hardware for making kits. The boards need a couple tweaks, but I've tried them and they seem reliable. I just gave him a call to see if we can find homes for those boards as well.
And of course I'm trailing the pack with the open source version
