I've only done it for my clinical instructors and its always a group gift. If the individuals want to chip in they are welcome too but I've never gone over $10 mostly its just a basket filled with goodies that are a particular fit to the instructor. For instance just finished my peds rotation and I put together a basket complete with coffee, a mug, and chocolate (our instructor is a choco/coffee nut).. It was a small jesture but it was enough to show our appreciation.. Now I never expect anyone to contribute and I say if they want they are welcome to but its not expected. Course we're talking at the most $1-2 each so that won't break the bank for most students.

I try to bring goodies as well for the unit even though they are not always receptive and for the most part have been nasty IMHO to us as nursing students I get more respect at my job as an extern which is really sad.
Course have to add I only do it for those instructors that embody the type of nurse I'm striving to be! Enough of the damn "real world" already.. I'm so tired of nurses who use that as an excuse to substandard nursing care.