Sydney does seem quite expensive, but I'm okay with it.
You want to work as a developer on cool projects, and you want to live somewhere nice.
That sums it up. I have been traveling and working remotely for 2+ years now. It was fun a while, but I don't see myself doing it in the long run.
Remote working doesn't necessarily mean travelling. I've been "remote" working since 2009, and in that time I've lived in 4 houses in two cities (2 in Melbourne, and we've just moved into our second place since being in Thailand)
One thing to keep in mind is that the 'startup' industry is much less active in Australia, and in my experience salaried tech jobs (as opposed to contracts/b2b consultant type work) in Australia in general are quite low, unless you're doing doing "enterprise" stuff for government/banks/etc.