Are you wanting to light this for live plants or just for a new look?
Your best bet might be to get 2 x 36" fixtures. Or, you could consider metal halides.
We have a 72" compact fluorescent light on our tank, that was from a manufacturer going out of business, I believe it's a 2 x 96w fixture.
You could try
www.aquatraders.com, but you would probably have to change out the saltwater-type bulbs, which could cost extra (although you could sell the SW bulbs on eBay, etc.). They always seem to have the lowest prices on lighting.
www.petmeister.com also has some good prices, and some of the fixtures have a choice of bulbs.