Last week I booked a flight Kuala Lumpur - Tehran - Kuala Lumpur via Summit Air Travel (www.flyme.com.au) in Sydney for $950 Australian dollars INCLUDING tax on Iran Air. Good price. Nothing else cheaper. Travel agent is very kind.
I will fly Sydney-KL-Sydney on Jetstar (which I can book online myself for about $800 on jetstar.com.au). But don't delay, Jetstar are pulling out of Malaysia next month!
The other option is to get Iran Air from Bangkok - Tehran - Bangkok and then hook up with a flight from Bangkok to Oz (there is a whole heap of airlines flying from Thailand to Aust).
The Iran Air flight is on a 30 year old 747. Not the best, but you get what you pay for. They only have 2 flights a week to Malaysia - so I have to fit my schedule around it.
On bestflights.com.au there are a few other flights a little bit more expensive on Qatar Air, Ethihad and Emirates. But they will all cost more and involve 2nd and 3rd transit stop, so I think Iran Air is worth it.
My concern now is how long the Iran Embassy in Canberra will take. My application is now in the works being processed!