is it more cost effective buying a chanel at an airport vs. at the boutique?

Vienna has Burberry and Hermes, but none of it is duty free AFAIK, you can only profit from the sales season at Burberry. Then there are small Bvlgari things which are a bit cheaper I believe
 
that's interesting to hear that some brands are cheaper at int'l airports, but given their small sizes, is the stock better? like, would those be someplace i'd call when i want something relatively hard to find?