In my post I’m on a budget. Which city should I fly into?, I discuss the benefits of flying to Adelaide. The only thing I wish to add, is that whether you buy an economy ticket or a first/business class ticket to Adelaide, your ticket – in theory – should be cheaper than flying to other Australian cities with arrival caps, because on planes flying into Adelaide there are more passengers to share the cost with.
In order to get a ticket for any sort of reasonable price, however, you may need to book many months in advance.