M.O.
I'd get the teacher a gift no matter what.
As for the sub, how about a small container with "homemade" sugar scrub? That's what we did for our bus drivers.
Take a container (pref. plastic with a screw top lid), fill it 80% with regular sugar. Dump the sugar into a mixing bowl. Add in some fragrant soap or shampoo - about 2-4 T. (we got apple shampoo at the dollar store) and then add in cheap olive oil. Add in enough olive oil until mixed well and all sugar is coated. Pour into container and add ribbon with a note.
You just scoop some onto your hands, scrub and rinse with warm water.
It completely dissolves in water, so no risk of clogging drains or septic systems.
It makes your hands SO SOFT and smells great! And it's really cheap, and the kids really love making it.