Why is liquid yeast so expensive?

Was just wondering why liquid yeasts, like Wyeast, are so pricey here, when they are so cheap in the States?  I mean, an Activator pack is about  $6 USD ($7.64 NZD) (http://www.northernbrewer.com/shop/brewing/brewing-ingredients/beer...) while a good dry yeast is only a few dollars cheaper at about $4 USD.  A quick browse of the NZ homebrew sites shows that Activators sell for around $20-25.

I was doing some rough calculations to see if this discrepancy extended to other brewing consumables from the States, but it seems to be limited to liquid yeast.  E.G., Danstar Nottingham is $4 USD ($4.80 NZD) (http://www.northernbrewer.com/shop/nottingham-ale-yeast.html)- only a few dollars more over here.  Also, 1 oz of US cascade is $1.75 USD ($2.14 NZD) (http://www.northernbrewer.com/shop/cascade-pellets-1-oz.html), which is abut the same as here (if scaled up to a 100g pack).  

I was thinking that may be it was a transportation issue?  I suppose liquid yeasts have to be transported cool, but I was looking around and saw that Hashigo Zaki also import their beer cool to make sure it is as good as possible.  A quick check of the cost of a bottle of Green Flash Hop Head Red from HZ is $6 (http://www.cultbeerstore.co.nz/collections/green-flash/products/hop...), where as it is $3.39 USD  ($4.14 NZD) from the first US online beer store I found from Google (http://www.halftimebeverage.com/browse.cfm/green-flash-hop-head-red...).  This is not too much of a difference seeing as this has come all the was from the States (props to HZ!).

Am I missed something here.  Are there loads of hidden costs associated with importing liquid yeast compared to other stuff.  

Puzzling.