For stationary macro subjects, a simple DIY light tent is one of the cheapest and most effective options. Drape a white cloth or thin bedsheet over the subject to create a small tent, leaving a hole for the lens. Then place two matching lamps outside the tent to diffuse the light evenly and reduce harsh shadows and reflections. Using the same type of bulbs in both lights helps keep color consistent.

Because this setup may be fairly dim, use a tripod and longer shutter speeds to compensate. That works well since your subjects aren’t moving.

If you want a low-cost non-DIY option, a basic LED macro ring light can also work well for very close subjects because it provides continuous light right around the lens. It’s not the same as a macro flash, but it can be a simple budget solution.

So the best cheap approach here is: DIY diffuser/light tent + two lamps + tripod.