i use a couple of circuit-bent casios around the house, as well as speak-and-spells and stuff. also, i managed to "borrow" a theremin from my bass player when he left it at my house when he moved.

my favorite cheapo board is the Golden Camel. a little background: in the early and mid nineties Camel Cigerrates had this promotional thing called "camel bucks" or something, and you could buy things using the upc's from cartons. one wasthe Golden Camel keyboard. it had buttons and sliders, which apparently did nothing since the actual keyboard never changed from a honkie, mid-rangie triangle wave.