My daughter in law is a teacher in a small town in western Wyoming. Each year she has to spend hundreds to have special books she wants to use in class, any special art projects (holiday stuff), as well as buying reams of paper to copy off her lessons. Worse yet, sometimes there isn't even toner for the copier so that becomes a problem. Schools have the same problems we do... everything costs more for them too, rising health costs, liability insurances, property insurances, repairs, maintenance, equipment, food costs, cleaning items, etc etc etc. Yes, taxes go to pay for all of this, but to cover the rising costs, taxes have to go up also. Teachers pay isn't all that great either. They are entrusted with the care of 20 to 30 children roughly 8 hours a day, 9 months of the year. That doesn't include all of the time at home doing lesson plans, taking the required education credits to stay certified and volunteering to be coaches/leaders for school activities.
She has also been known to send peanut butter and jelly home with crackers because the children will not have food for the weekend in some cases. It is a real problem, not just some made up boo hoo sob story.
Please consider giving them supplies for gifts instead of another mug or plaque or ornament. They can use supplies for a real purpose and let's be real, no one needs/wants another "greatest teacher" mug or wooden apple for their desk.
If you can't afford to buy all of the items, talk with your school counselor or church and they can help point you in a direction for some aide.