Mr Vintage (.co.nz I think) has cool kiwiana t-shirts for babies and toddlers. 
Some cool things we've received from friends back home - Longest Drink in Town onsie, "Made in New Zealand" t-shirt, other kiwiana t-shirts, a pukeko mobile, Lynley Dodd and Margaret Mahy books.  Oh!  And an All Blacks rugby jersey 

 and baby rugby ball.