I use 2 double shoplights, so 4x32W T8's (6700K Phillips). I did gut them & mounted the parts in the canopy at 3" or so above the water. It is giving me good solid med light. I have room to mount 2-4 more T8's if I want. <Mounting it 6-12" above the water prob won't be too bad, you lose a little bit from scatter, but I wouldn't worry unless you are mounting the light on the ceiling or something.>
The shop light route would be the cheapest, but at the rate the T5-HO
's prices are coming down, I think a 2x54W T5HO would be a nice one for that tank as well.