You need to recheck your data on that. The average also includes principals who make $80-$100,000. I have taught for 9 years and make less than $40,000. I got an $8,000 raise this year-that is how bad our pay HAS been. Our state is finally realizing that they need to pay a decent salary to keep good teachers.
I think about the amount of time my DS spends with his teachers(almost as much of his awake time as he spends with me) and I feel blessed that they do such a great job with him. If your child(ren) have teachers who go the extra mile to make them feel special, it isn't a big deal to give a $10 gc once a year to show you appreciate them! If you don't appreciate them, don't give anything.
I am always appreciative of home-baked goods. That being said, I don't usually eat them, because of just not knowing if someone washed their hands, etc. Maybe that is weird of me, but I even worry at restaurants. I have had food poisoning a few times.

I share with other teachers that don't have that problem-I don't throw it away.
Best gift for me was a restaurant GC last year from the whole class. It was $75 to Outback!
One thing I saw suggested was to write a letter to your child's teacher about the difference they have made in your child's life and cc the principal. It will make the teacher feel so appreciated!
Marsha