When buying or making a lighting system, several other factors not mentioned should be taken into account. First, what does the lighting system look like on top of your tank? If you DIY, will it be something you are pleased with? If not, then a retrofit or a custom job might be the way to go. Second, are you able to DIY wire and be worry free once you are done? If not, a custom job or premade may be the way to go. Finally, if you DIY, do you have the option to fit a good type of reflector inside the hood? Adding a good AH Supply reflector or reflective mylar to a DIY or premade hood makes a world of difference--you dont want light spilling out all over your room and not going into the tank.
All and all, I have a double 2XODNO hood on my 55 g for a little over 200w. If I had to do it again, I would but a kit from AH Supply and built one out of PCs. Im very interested in T-5s, but sadly not even Home Depot carries any Plant and Aquarium type T-8s (48 inch) where I live.