Pakistan and Iran. I can't believe that these countries are not swarming with budget-conscious travellers.
Given your experience in other South Asian countries and Egypt, you will find Pakistan a breeze. Compared with India, you will appreciate the respect for personal space and the relative cleanliness. One AUD is currently worth about 100 PKR. Accommodation is cheap. Local transport is cheap. Food is cheap. People are extremely friendly. And it's highly unlikely you'll run into another tourist. July is extremely hot in the Punjab and Sindh provinces, so take a break from that with a journey up into the high mountains through Gilgit to Hunza and beyond. There's a different culture in every valley. You must get your visa in before you leave your home country, but the embassy in Canberra and the consulate in Sydney are both very quick and efficient in issuing visas. In November 2012 I found a one-way ticket from Bangkok to Islamabad and Lahore for about AUD 207 by booking through the Pakistan International Airlines website.
Iran is a much more developed country than Pakistan with fantastic transport infrastructure and plenty of accommodation options. It has outstanding tourist destinations in Shiraz, Esfahan, Mashhad, Tehran and Tabriz. Because of economic sanctions, the currency has taken a beating and has lost much of its value over the past year. This is extremely bad news for locals (importing essential goods, including medicines, is prohibitively expensive) but extremely good news for foreign travellers. When I was in the country in December 2012 I was getting 29000 rials for one USD, now the rate is closer to 38000 rials per USD. I paid the quivalent of USD 21 per night for an apartment in a hotel in Mashhad, now that same place would cost around USD 15. I paid USD 7 for a VIP bus from Tehran to Tabriz (reclining business class seats, snacks and movies), that cost is now closer to USD 5. Search for any traveller's reports on Iran and you'll find only positive stories about travel there and the friendliness of the people. You can get a visa quite easily, either in Australia or from a consulate elsewhere, although there are two steps to getting it. Note also that you need to carry all your cash with you as international bank and credit cards don't work there, and you can't get money transfers via Western Union.
Of course, in both countries women need to dress modestly and with regard for the local cultures. There's plenty more information on visas, travel options and other matterrs in the relevant country forums.
