about $1500 AU
take it to the Toyota dealership and ask them to replace it
Pretty sure its the same as the 2000 Toyota echo, see related link.
when it breaks
$1500 to $2000
You can replace your 2003 Toyota Echo antenna. Remove the antenna retaining nut. Remove the cable from the bottom of the antenna. Reverse the process to install the new antenna.
$250-300
go to dealer
$5
You can access the bulb from the trunk area (from behind). Just remove and replace, should be straightforward.
How to open hood on Toyota echo
yes
There is an access panel in the trunk. Its very easy to change the bulb.