I believe many of the hobbyist step into the world of aquatic plant will consider few things, such as setup budget, equipment cost, fertilizer, heath of the plants and etc. As I can share about this budget aqua light, because I have 2 used T5 12000K fluorescent tubes that kept in the storeroom. Normally once a year I'll change the tubes for lighting efficiency to grow some healthy plants.
The top photo is the China made double T5 tube housing ceiling light with electronic ballast just cost around US$18, but it came with the normal fluorescent tubes. What I do is replace the used 12000K tubes and place on top the tank, it works good for aqua light. But the back portion of this ceiling light need to cover with waterproof material, such as PVC, plastic, metal of others, that is to prevent the open case cause electric shock by water.
After tested for a day, some plants show the good sign of photosynthesis happening with add on extra wattage. Perhaps you can try it too, low cost high effective light fitting.