Send your special someone a message on Valentine's Day in your local newspaper. Free in QLD/SA/NT and also VIC (despite the 5 line minimum mentioned on the website). In NSW, the Daily Telegraph costs $32.75 for 5 lines.
The Advertiser (SA)
3 lines free, additional lines $5, no minimum lines They have now changed this to $20 for 5 lines and $5 per line thereafter. Poor form!
Courier Mail (QLD)
3 lines free, additional lines $3, no minimum lines
NT News (NT)
3 lines free, additional lines $5, no minimum lines
Herald Sun (VIC)
3 lines free, additional lines $11.28, 5 lines minimum (not enforced - see here) EXPIRED
More than one member reported in comments that they were able to post a free message in the Herald Sun despite the 5 line minimum mentioned at the link below.
OzBargain is running a Valentine's Day competition — so post a love message to OzBargain in the newspaper. $50 Gift Card plus some T-shirts + Bags up for offer.
Some entries from last year's newspaper with mentions of OzBargain.