4 light fixtures are very much more expensive than 2 light fixtures and then theres the cost of the bulbs. You don't really need four lights You just need a 2 light fixture with wider wings. I have 2 with a 13 inch width on a table 3 feet by 4 feet and they work very well. I can get 6 trays under them. The ones in the center get a bit less light but I move them around every time I water. I have them connected to a power bar and that's plugged into the wall.

I have seen them with a 9 foot width and that would be fine on a shelf. The major thing when buying lights is to have wings so the light is concentrated downward.

I would check all the hardware and big box stores that you have in your area on line. You might be able to find some on sale and them you can go into the store.

As for shelving look in resale stores or second hand stores and think outside the box. Remember you have to hang the lights on something so I'd stick to wood

Thanks for starting threads. I am facing same problem as you and eager to get solution.