i also have a pretty thin face, but have found that there are several oakley styles that fit very well. currently i have the fives 3.0, which i really like.
i think you can find them for about $70 w/out polarized lenses.
also, the oakley mag four S sunglasses are built for a thin face, but i don't think they look as good as the fives.
secondly, if you're going to buy some shades and want to save some dough, i recommend checking out the sunglass section of
backcountry outlet . they don't always have the widest range of color choices, but you can usually save about 50%.