I am signed up for a still photography class.

I use a Canon A40 Powershot for work - I point the camera, press the button, it takes good photos.

The instructor suggests a better camera - but he also said I could get a close up lens for the Canon.

Any suggestions on what I should buy - or not buy?

I don't want a camera only for close-up photos but that would be the primary use at this time.

I would suggest getting the lens. It would do what you want to do just fine. I took thousands and thousands of pictures in the days when digital cameras were not even thought of. I used a Canon AE-1 and had many different lenses. I took prize winning photos using this camera. I also took several courses in photography as well.

If your going to invest in a photography course look into buy an inexpensive digital SLR (the type that allows for the lens to be changed)
I'd recommend a Canon Rebel XTi - here are some Canadian prices - Canon EOS Digital Rebel XTi Price Comparison
You can get any lens you want including a macro or "close-up". I think it's usually kitted with an 18-55mm.

Happy Shooting!

You will have to get SLR camera. Chose your brand carefully. But Canon and Nikon are very good brands. I suggest that you go to KenRockwell.com. There, you will find all the info about the subject as you ever need to know