My local Woolworths are selling the Motorola WX160 for $29, which includes $20 credit so essentially the phone is $9. It's a very, very basic phone but great for people who don't use their phone that often as it has a 100 day credit expiry.
On the website, it's still listed at $39 but it was definitely in my local store (Aberfoyle Park) for $29 so maybe it's worthwhile checking with your local store.
mod - **Everyday Mobile uses the Optus network. Uncertain if the phone is locked to the Optus network, Everyday Mobile or … **
"Pick up a Woolworths Everyday Mobile Pre-Paid Mobile Pack for just $39" The site says its $39, still a good deal though.