Have you looked up OTEN? I've gone through them a few times, and they're pretty much entirely online, and you email your assignments in through their website, or you can post them in. It's a division of TAFE, so you would be able to get the concessions/exemptions if you get centrelink benefits.
The fee for the courses was $0 for the actual course if it's the first of the year ($50 for every course after that) and a $50 handling fee for materials as they often send out CDs with materials and also paperwork.

I found OTEN awesome! You don't have deadlines for assignments, and you can take everything at your own pace, you can finish a course in 3 weeks or 3 years if you really wanted! (You'd just have to keep paying the necessary fees if it's relevant obviously lol)

Eta - as for the actual exemption, you just tell them when you're extolling, and give them your centrelink details on the enrolment form, they check it all, and if it matches then hey presto it's done