Hi,
How 'bout going to the internet and getting a cute pattern for a 'gift card'. Making the card will be inexpensive and will personalize the gift...then put a gift certificate to Baskin Robins or Dairy Queen inside. You can even make up some silly pun like, "A sweet for the sweet who helped me make it thru the school year".
Or you can buy an inexpensive plastic or terra cotta 5 inch flower pot and decorate it with paint, lace, buttons, stickers (if you decompoge over it) and then put a bright flower or plant in it. I recently did a small terra cotta pot with a silly face and planted a fiber optic grass in it. The grass looks like hair and is a really neat little plant to have should the receipient ever want to transplant it. I have also done lacy pots with Coleus and old-fashioned stickers on a terra cotta pot (decompaged before adding the plant) with moss rose. Just choose a planter style and a plant that complements the sentiment you are trying to express (silly, sentimental, classy etc)
Another thought, if you are into jewelary art, would be to make a bracelet or earrings. Both can be done fairly inexpensively but be very classy gifts.
Hope this helps,
V.