Estimated time to complete activitiy:
variable

Materials needed:
Sports bottle OR spring water bottle

Gift certificate to a sporting goods store

Ribbons, perhaps balloons, to tie to the bottle/decorate it

Note/card of appreciation

Description:
Its...just a decorated sparkling water/sports bottle thang with the certificate attached/inside the bottle.

Instructions:
Customize it yourself!

Those of us not independently wealthy would quietly solicit contributions from other classroom parents.

Other suggestions or comments:
Many of the teachers take Walk Breaks for fitness (and stress-busting) vs. Lunch Breaks. They grab something to eat during the time kids are with specialists (computer, music) or at recess. I feel pretty sure that by now they'd love a new pair of shoes, or other cool gear for summer. The younger the teacher, the greater the odds this might be more pleasing than a huge bouquet of flowers. Appeals to both genders.

If you ever see a li'l pair of worn Reeboks/Nikes stowed under the desk, sad after surviving all those Field Trips, ponder this possibility. You can likely collect enough to still afford a smaller floral tribute.