First I would say how handy are you? Where do you live? thats alot to pay for fluros.. I come from the fish world which is were i learned about overdriving lamps if you feel that you can work safely with electricty wiring in the off stage i say look into that.. For 150 bucks i could have 5 100w fixtures. no problem but very little heat.. right now I run 2 2-light fixtures that hold 2 40w overdriven.. dont belive it makes a diffrence.. check this out.. one side done one not.
I think you know which is overdriven.. i search real quick and give you the percentage that it bumps them. it does make the lights go quicker but i could probaly still pick up 10-18 lamps cheaper than one 400w mh horti bulb.