i have the same problem. My girlfriend has size 5 feet and nothing highend fits that well.
right now, she rides XS byerlys.
Allen is right, in the off-season, ebay has killer deals on xs bindings. We tried on the small Minx and they were too big. I want to get her some highend bindings, but they dont make them small enough.
Todd, please let me know if you find some bindings that fit.