Baz, you can get them from Centre.net for a good price.
$91.08 inc GST
It is the 'Canon ACK-DC20 AC Adapter Kit' for 'Canon Powershot S80/70/60 Digital Cameras' but it is the correct one for the Rebel Xti/EOS 400D Digital SLR Camera
http://shop.centre.net.au/index.html...7Q2&it=product
If you scroll down on this page, you can see it listed - Canon ACK-DC20 AC Adapter Kit (and it links to the same link I gave above).
http://centre.net.au/Canon_Digital_R...ck_000642.html