Ask them what they're offering. If they say they don't know, walk. Any reasonable business will (a) be honest, and (b) have a budget sorted before they post a job-ad.
Bring-up money late in the job-interview if they don't raise the matter.
Surprisingly, I've found job-pimps to be more forthright about pay than employers, and it's probably better to get a ballpark figure at that stage.
You can afford to compete on quality, not price, so don't think you're under-cutting anyone. Seriously, leave that field blank if there's a form prior to an interview -- you're not impressing anyone, only sticking your neck in a noose.
Keep in mind that contract rates are approx 25% higher than salary rate since you'll have to arrange your own super, business-insurance, health-cover, and you don't get paid for sick days or holidays. These things balance-out...if your job is advertised and then managed by an agent, then they take a cut but it's (mostly) worth it sine they do all the bookwork. And they can terminate a contract on a whim.

You might want to contact Mark Morrison (details via the Arcanacon website?) about the writer/GM to game-designer route.