While my kids were in school, up to 8th grade, I sent in gifts for the classroom teacher. They just had one, so usually it was over $10 but under $20. When they hit middle school (it's the same school with us) they had 6 different teachers so I usually bought smaller things, probably about $5.00 or baked something.
We also are asked to give $20 at the beginning of the year for gifts from the class for Christmas/Bday/End of Year, etc. I've never NOT given an additional gift. Teachers work way too hard not to be appreciated!
As a teacher myself, I love getting gift certificates to anywhere, especially teacher stores. Have way too many ornaments, mugs, bath and body stuff, candles, picture frames and such.
My only advice to parents, try to get something that doesn't scream "cheap"... don't mean to sound nasty about it..... but I'd rather get nothing than something from the dollar store.
Forgot to say, I teach at a private school in a very affluent community. I've lived here my whole life, I know that of which I speak! I certainly would NOT care about something being from the dollar store or even being a construction paper card if my students/families were public school and/or from an area that was not very affluent.
Hope that came across right. Not trying to slam here.