I bought this at BestBuy:
http://www.bestbuy.com/site/insignia-mini-displayport-to-vga-adapter/5813139.p?id=1219159701631&skuId=5813139
It worked for one day. Then windows downloaded an update (on 10/06/14) and the next day it no longer worked from either the SP3 port or the docking station...