Actually!
ok 3 rigs costing you $107/month right now. If you put all your GPUs into a single rig, retired the other 2 rigs, you'd actually be paying less than that. A noticeable amount less. By using 1 rig, you eliminate having to power 2 southbridges, 2 northbridges, 2 hard drives, 2 optical drives, 2 sets of RAM, however many fans are in the 2 rigs, and, the biggest chunk of them all, it's 2 CPUs you no longer have to power. Also, the 1 rig will create less heat, saving additional money on home cooling (though requiring more heat in the winter). I'm betting by combining everything into 1 rig, you save at least 30% per month off that bill. Maybe 40% since you're tossing dells