Are you going to use a lid, or do you already have one of those hoods where the light just sits on top of a glass pane? I do, but I swapped the t8 housing for a twin lamp incandescent model that cost like 12 bucks - and put a pair of CFLs in it. Easiest and cheapest solution for me.
I have a clip on desk lamp with a 6500k CFL for my 5 gallon - two of these would work just fine for a 10, but they are more expensive than the cheap hood mount fixture. I use 2 10w 10k bulbs in the low tech 10 gallon, and 1 18w over the 5. I probably wouldn't go over 18w bulbs, even with co2, or you'll spend more time trimming plants than looking at the tank.