Macro or Closeup filters are the cheapest way to shoot macro images. You could easily attach a filter onto any lens you already own and start shooting macro images.
Reverse Lens is a technique where a normal non-macro lens is attached to the camera reversed to effectively turn it into a macro lens. This works with nearly any camera lens combo and produces excellent results.
Macro photography is defined as the genre of photography where the size of the photograph of the subject is larger than the subject in real life.