Ok I talked to the photography teacher and he said that it would probably be better to go with the 18-55mm IS lens for his class. So I got my Amazon cart ready this is what is in it.
Canon Digital Rebel XTi 10.1MP Digital SLR Camera (Silver Body Only)
Go black, if you can.
I'm personally not a fan of filters, especially cheap ones, on such high grade lenses (except for polarizers, neutral density and graduated ND). Forego the filter for the hood.
I read some stuff about having a hood for the 100mm Macro to protect it but someone else also said that a protection filter will do the same thing. And the Tiffen one comes free with the camera.
The Canon 100mm macro is unusual in that its front element is far forward. Most have the front element recessed. This becomes a potential flare issue. Canon has engineered a rear diaphragm in the lens to reduce this possibility at f/2.8, but hoods are always a good idea. It will cut down on flare and afford some protection of the front element. In 30 years, I've never damaged the front of a lens, while others have.
Or is the $39 piece of plastic worth it?
Yes, I would. And for your other lens as well.
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.