Thanks for the replies.
We went to Wellington a few days ago (great city...), and managed to find a Spirograph set after a long search. We found it at the Whitcoulls downtown. It's the same as the one showing on Deborah's link, but at only $12.99. The kids have been loving it since opening it at home.
It's much simpler than the version from 30 years ago that Sandrine & I remember (that'd be France and Canada - got around pretty good, that toy...). But it's really a lot of fun for kids of all ages (including Mom & Dad!).
I teach math, and would add that it's a great way to learn hands-on about such things as polar co-ordinates - which is usually covered as late as in 2nd-year university. So, when they say it's for ages 5 and up, I guess they're right...
Cheers,
Rob