Alex Inglizian and I are doing 37 mini-hacking workshops at branches of the Chicago Public this summer (2011). For all those jumping speakers and little amplifiers we need a lot of 9-volt batteries. I ordered them from a joint in Brooklyn with the delightfully disturbing domain name of "cheapbatteries.com". 488 batteries weigh exactly the same as a Bryston 4B amplifier (I hefted a lot of those in the 1980s working for Studio Consultants). I feel like a cabinet minister in a low-voltage OPEC nation.