At my dd's Waldorf school we collected (whatever you could afford) from all the parents and gave the teacher cash (about $150.00 each for 4 teachers, 2 in each class). Teachers at our school have to pay for their own training in the summer (they all have to go) and it's not cheap, and the pay is not the best (they truely do it for the love of children). Some parents also gave direct gifts in addition to the group gift, like homemade holiday cookies, knitted items, gift certificates, wine, wool for knitting (knitting is big in Waldorf, lol).
We also have specialty teachers (languages, gym, handwork, claymolding, eurythmy, music, etc. These teachers got about $90 each, all the parents in the school contributed to that gift. There was also a basket full of homemade cookies for every teacher and administrator.
Those who have very little $$ to spare bake, knit, do something, it's jsut the way Waldorf is, community.