help buying a garmin oregon 450t gps

I've been looking for a Garmin Oregon 450T. Everywhere I look in Australia seems to be very expensive. Does anyone know where I can purchase for a reasonable price? Or, just wondering if anyone has ordered from overseas (for hundreds less), taken off the pre-loaded US/European maps, and replaced with Australian Topo maps. Will this work? Thanks for any advice anyone can give. Cheers.