wow...we are on a leccy meter and I've got my set up down to about £10 - £15 a week to run and that 2 tents. Cob lighting has saved me near on £10 a week.
I've got 2 600w hps, 2 400 hps plus a shite loads of fans filters etc.
I will soon be switching my veg lighting to CFL once the weather gets warmer.
Ps I just checked again and it's roughly £160 a month but that's including the leccy and heat for my house too