If the gift is not expensive enough, then you are seen as a cheap-skate or perhaps as being rude. If the gift is too expensive though, you can create an awkward moment where the recipient feels inadequate for not giving something equivalent or as now being beholden to the gifter.
Then of course there is the question of the gift itself. If it's something the recipient has no interest in, then he or she will perceive you as being thoughtless or inconsiderate. If it's something they already have, then all you will get back is that awkward smile of feigned gratitude.
The principle question then before me was therefore what would Captain Jean-Luc Picard want for a Christmas gift?
There is only one solution. To Wal-Mart!