I used two double bulb 4' shop lights (four bulbs total) for almost a year on a 40-breeder. I used the daylight 6700k bulbs from HD and they worked fine, and cheap. I bought a whole box for what a single "proper" fish bulb would have cost.
When you buy the lights, make sure you get the ones with the plug built in (as opposed to the ones you have to hardwire into an electrical circuit, unless you want that). Also, some lamps have the bulbs slightly recessed so that you can put them on a support underneath. On others the bulbs stick out so you have to hang them. Just make sure you're buying what you expect - things are often badly labeled at my HD.
You definitely want to have a cover over the tank, obviously. Either glass or the acrylic panels for drop-ceiling lights, if you're feeling particularly frugal.