With no plants the lighting is really only for your viewing and for the fish to sense some sort of day night cycle. If you never plan on plants you can go with some nice LED lighting that doesn't need to be plant friendly. Light dispersion is not an issue, it's only aesthetic, so a 24" in a 30" isn't a problem... I did that with my LED setup and have tons of plants, so it's not a problem even then. Going with 6,500K would be good for plants but is extra cash that you don't need to spend... same thing with the 10,000K which is not useful for plants either.
Not that this is the best option, but one would be the Marineland single bright 24" to 36" fixture. It has sliders to extend the span of the tank and you can leave the fixture itself to one side or the other or just leave it in the middle like a regular hood would be.
Here's a link to their info page
You can get that for under $100 easily... Probably around $60 and you shouldn't have to worry about replacing bulbs for some time.
If you check out my tank that is a 24"-36" LED fixture slid over to the left side as far as it goes... It's double bright so the light is a little more focused as there are 8 bulbs as opposed to something like 50 in he single bright (8 x 1 Watt vs 50+ x 0.065 Watt bulbs... less bulbs doesn't mean less light)