I’m constantly amazed anyone buys anything from BAA duty free or tax free shops or whatever they call them. Just about the whole of Asia and IIRC NZ have real duty free upon arrival anyway.
As ExSimGuy so rightly states BAA are ripping customers off and local supermarket prices are cheaper just about everywhere. Here in LOS I (used to) pay ₤1 for pack of B&H and (still) pay ₤4 for a litre of gin.
Probably the only item I can’t get cheaper in my local supermarket is a 45 X 35 X 16 briefcase as they don’t sell them!!!!