I'll just add that the cfl's seem to last forever.
I have the 2 desk lamps in the MH. Which I tend to leave on all the time cause of my need for bright light. I was replacing the 'regular' bulbs what seemed like every month. (I think they actually burn out faster than years ago).
I'm on my 2nd year with the same CFL's now. I think the payback on their price is almost instant. And for me having eye problems the availability of being able to buy a 6500 kelvin bulb is price less.
If you have any type of problem with your eyes reading etc. 'especially' inside a MH. Buy a 6500 Kelvin bulb you will be VERY surprised how much it will help you. Even if you don't have eyesight problems the amount of bright white light it brings to the inside of a MH is unbelievable.
So far I have only been able to find them at of all places Walgreens and most Home Depot. Lowes does not carry them.
