I think the clue is in the title. 1000W that is 18 kilowatt hours a day. I pay 9.17p per kilowatt hour here in the uk which translates to
18 * 0.0917 = £1.65 ($2.48 ) / day
during an 18 hour vegetative cycle. This is using the nominal rating for the bulb, it'll actually use more, but how much more depends on what temperature you keep the ballast. A cool ballast is a happy ballast. Note this figure also doesn't include the fans. Running a 1000W bulb is a serious investment.