Thanks for all the feedback in this thread. Based on all of this info, I've concluded that my project is just not economically feasible given the complexities with providing adequate power to 2 onion devices simultaneously. I was hoping to build some kind of audio/video based home monitoring system (using 2 different onion devices -- one w/ a camera, and the other having a USB speaker attached) .. and so far I've calculated an absurd cost of just under $200.00, -- without any kind of enclosure, or guaranteed reliability. And then I came across this cool little gadget, and gave up entirely:
I'm still quite fascinated by the Onion and am curious about it's possibilities, but I'm certainly not going to re-invent the wheel - and certainly not at 8x the cost !
Thanks again folks!