Quick effective with minimal fuss and fee?
Take all those nice fancy lethal injection tables or chairs and retrofit them with a doughnut shaped head piece and cattle gun on a swing arm. Strap convicted SOB in, swing cattle gun into position behind the head, push button and send the bolt up into the brain bucket severing the brain stem and turning everything else up there into scrambled eggs. No missing, no "oops" that prolong the death, no multiple sticks to get it right, no "we're not supplying you with those drugs anymore" or medical industry moral dilemmas, instant death about as guaranteed as you can make it, reusable, cheap, and leaves everything else intact for organ harvesting and such. Hell, if you want to do the not knowing who flipped the switch thing, it should even be easy enough to rig up a multi-button control panel with a computer randomly selecting which button is the hot button for each execution.