Macro Photography for Beginners: Add another lens back to front to your lens.

Sounds silly but it works, it really is a more fancy example of adding a close-up lens. To do this you have to obtain a lens coupling ring and maybe some stepup or stepdown rings to suit your lenses.
The best effect is obtained by using a long focal length on the camera body and have a short focal length lens reversed in front of it. Say a 200mm lens on the body and a 35mm lens reversed in front. Some experimenting is possible just by holding the two lenses together or maybe by taping them together with gaffer tape.

Upside. It`s cheap because you probably already own the lenses and only need to get the coupling rings. You can test the effect by carefully holding them together. Can use any brand lens as the front lens.
Downside. The image will suffer a bit due to the many extra glass elements you have added, extensive experimenting is the only way to see what happens. Prime lenses will yield a better result than zoom lenses. The front lens has no aperture control so you may have to manually set it (if possible) to experiment with the possible combinations of aperture settings in both lenses.