The entire energy bill w/ electric heat, water heater, stove etc. no gas in the house was $200.00 a month, every month... that was a 4 bed 2 bath 2 story house w/ basement. And I always had other shit running up the bill, tv, stereo... lights... etc.
It really doesn't run up the bill too high at all, each 600W digital ballast runs 5.5 amps, so the total damage is 33 amps 12 hours a day. If you have a portable heater, use a toaster, microwave, hair dryer, etc... read the amperage on those. Another thing is I have a 20 amp compressor, and tons of power tools and air tools, a welder etc.. but I don't use them very often. They could easily be responsibe for a whole lot more amperage than my ballasts.