Experts are still trying to come to grips with what drives New Zealanders crazy over supermarket collectable items.  

In the two weeks since Countdown launched its Lego-like brick collection - shoppers are already reselling the items online for as much as 200 dollars.  

Victoria University clinical psychologist Dougal Sutherland told Mike Hosking he doesn't quite understand why it sends people into a frenzy. 

“Every now and then you just get this crazy thing that everybody gets into. I think if you could pick it before you went into it, marketers, it would be heaven for them.” 

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