would probably go with a hid for flowering and use flourecents or cfl for veg, hids can use alot of electricity but for the amount of light they produce they are very efficient and if you just run it for flowering 12 hours a day then it consumes much less than if you used it for veg also at 18-24 hours a day.
really depends on how large of a grow you want to setup if you just need one hid 600 watts or less its not going to make a large difference in you electric bill if you want 3000 watts of hid then it can get quite expensive on the electric bill.
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