Any reason you need T5HO? I use a $8 fixture over my 75g. Dual 40w (I think) T8 bulbs. Picked it up from Lowes or Homedepot.
Edit: Here's what I got, I think they went up a bit in price but they are 40w T12's.
Shop Utilitech 48" Utility Fluorescent Lighting at Lowes.com
Don't let the reviews fool you either, they all complain about ballasts failing after years, which they all do. Costs you $2 for a new ballast. I have about 5 of these in my house, 3 in garage, 1 over tank and 1 over laundry area. Only 1 out of 5 were a bit noisy so I put that one in the garage.
The nice thing is they come with hooks and chain so you can hang them.