In my opinion, unless you're growing a lot of live plants, going through the bother and expense of getting a hood, or even just a cover with lights is overkill for a Betta setup.
The traditional "hood" with light is common practice with larger aquariums. It provides enough light for any plants, even high to medium light plants. Betta prefer a darker environment, so low-light plants (Anubias, Java fern, Java moss, mossballs) are more appropriate.
I use an inexpensive second-hand-store desklamp with a 15W 6500K curly CFL (Compact Floresctn Light). My fish like it and my low-light plants grow just fine. I have a spotlighted half and a shady half in my tank. Very dramatic. I think it looks great. And it gives my fish a shady place to hide out.
(I did say, "...in my opinion," didn't I?)