How much in power costs are you actually worried about?
I have 24" deep 60" long tank. I am running 2 110w actinic vhos and 2 250w MH bulbs. The vho are on for 14hrs and the mh for 10hrs a day. I utilized this power calculator and input my kw cost off my power bill and calculated that it costs $20/month for my lights. Is this too much for you?
http://www.aquariumadvice.com/calcs2.php?type=electric