250 hps

I want to up grade to a 250 watt from cfl my electricity is 12cent a kilo watt how much do you think my bill will go up if I just ran it 12 hours and will I really see a diffrent in bud size

As far as your bill goes, I don't know. As for your bud quality and quantity, Yes, you should.

250/1000 x 12 *30 /10 = $9 month

^^What he said.