It's only $500 now though right? That's far too small. Putting yourself on the ballot should require substantial investment.
No. It's $2000 per candidate for the Senate, and $1000 per candidate for the House of Reps.
http://www.aec.gov.au/faqs/candidates.htm
Since you need a minimum 2 candidates to get a ticket for the Senate, which gives your party to a column of its own and makes it possible for people to vote for you above the line, it's really a minimum of $4000 per state.
Now that may not sound like much for you, but when us Pirates were forced to stump up $16k to put 8 candidates in 4 states instead of the $8k we had expected to before they changed the rules....well, that dramatically reduced the amount of promotional material we were able to make.
There's the opportunity costs to consider as well. Unlike the major parties, we can't afford to pay people a wage. That means the candidates and their teams can't take time off work to campaign, since they have rent or mortgages to pay and families to feed. As you might imagine, that creates a huge barrier to new parties starting up without some deep pockets to fund them.