Originally posted by FrancisK7 Five years ago I snagged one of the last two brand new Voigtländer 125mm f/2.5 APO-Lanthar macro lenses CQ had left. A year after that I sold it, at a profit, because I thought I'd never like macro.
I was so stupid.
Don't be too hard on yourself, we all can look back on decisions made in a different time or circumstance and wish we had the knowledge we have now!
In any event, the suggestions you've received so far will all work, and I'll add another. The Pentax M 100mm f/4.0 Macro. Manual focus, manual aperture, 1:2 magnification. I see these from time to time on eBay for $100-$150. This is a good starter Macro lens without a large investment and can yield great results once you learn to use it properly.
There is a learning curve to Macro, and your class will help in that respect. So will a sturdy tripod, cable (or remote) shutter release and split prism viewfinder screen. Relying completely on A/F for Macro is an excercise in frustration, or perhaps it is better to say all A/F systems have limitations which sometimes run counter to the photographer's intentions.
Once you have the equipment ready, I'd suggest going to a site where you can be assured of lots of subject material. The local botanical gardens or large public garden areas would be an example. Be prepared to spend plenty of time there and take dozens, if not hundreds of photos.
At first your "keeper" ratio will be low (if your experience is anything like mine!) but gradually the ratio will improve. The overall ratio may never be as high as it would for scenics or general photography, however, Macro is very demanding. It is also very rewarding!
Good Luck,
Ron