I got one from eBay by the brand name KOGAN. This guy does his own importing I believe so it keeps the costs down. They are very well priced and they are multi purpose too. Not only does mine have the nav software, but it will also play mp3's, movies, show pictures and allow you to read e-books. This is all covered by the SD card interface. Put the info on the card, plug it in and your away.
Good little nav system too. Showed tracks in the bush I didn't even know had names!
If you want more info I can try and find the email address somewhere..