I don't know of anything for $100, but if your budget is a bit higher, look at
http://store.yahoo.com/partshelf/ws2310.html That's a LaCrosse Technology unit. My impression is that LaCrosse are competitors to Oregon Scientific (also available through partshelf.com). They're selling for $168.95 USA and with shipping that comes to about $225 USA = about $335 NZ. FWIW they come with a disk of "Heavy Weather" software for Windows 98 (!). But "Weather Display", which is compatible with several LaCrosse and Oregon weather stations among others, is available for Linux (and is written here in NZ). =====Andrew
