Nothing to worry about
That might sound trite, but your growing weed here, which is like worth its weight in gold (before the recession). You will make, or save if your in it for yourself, the next 4 years worth of electricty in the FIRST HARVEST. So its not that big an issue.
Plus at 250 watts your bill is only gonna go up like 8-15 bucks tops.
I just dont know why ppl stress the electricty, the equipment is where you can fudge values.