Hi Stephen, I don't know much about this macro close up stuff but have you looked at a Canon 500D close up filter? I've seen some excellent pics shot with this attached to a 70-200 2.8 VR. Not sure if the AF works with the 500D?
http://www.rogercavanagh.com/helpinfo/18_500d-1.stm
What are they?
Macro and close-up are popular aspects of photography. There are a variety of tools available to the 35mm/DSLR user: extension tubes, bellows, specialist macro lenses. Another very convenient and inexpensive option is the close-up filter. I have the Canon 500D. Canon also make the 500 and 250D; officially, they are called close-up lenses, but filter is a more descriptive term because they screw into the front of a lens, where a standard UV or daylight filter fits, and magnify the image.