Free $20 to Spend using the code with no minimum spend. If you can pick up from their location in Osbourne Park, it's a freebie for anything $20 and under.
There are quite a few poster and rigid board variations that can be completely free (menu > large format Signage > posters or rigid board).
To use your own images/files, upload them after purchase at: https://www.easyprintandsignco.com.au/pages/upload
Some examples (many more on their site):