Is it inappropriate to ask for a salary specification when interviewing for a postdoc position? I am in the last year of my PhD (neuroscience/biomed research) in Italy and I have applied for an interesting postdoc position in Perth, Australia, at a neuroscience research centre affiliated with the UWA. 

The call that I have applied for is describe as “founded”, although without any hint about the actual salary. During the interviews and the few further emails with the new PI he has never mentioned the income, just stating that it would be provided “from internal sources” (so independently for grant funding) for the two years-contract. Btw he also offered me to help with visa, accommodation, etc, in case of hiring. 

I haven’t pushed this topic any further and I am still waiting for their final decision. Do you think it would be inappropriate to ask the amount of my salary and how should I approach it? I am very excited about the idea  to have a postdoc experience overseas, but I am sure that relocate completely will be a quite big deal and I am not familiar with the Australian cost of life, so knowing the actual income could help me a little to evaluate the whole thing.
I think it's a pretty common situation, during my applications I have noticed one of the two alternatives with regards to salary when looking for postdoc positions:


it's clearly specified in the job advert. This typically happens if the salaries are somehow regulated at an institutional level, thus there is little room for negotiation (if any at all). 
it's never mentioned, in the advert or during interviews. I have noticed that many hiring academics have the tendency to think that salary is not an important matter in the decision of an academic position. For the sake of the argument I'll not go into why that's a frustrating assumption, but the fact of the matter is that many group leaders assume that if you are applying for an academic position you have sorted out your priorities and the salary isn't on top of that list.


Let's come back to your case at hand; I don't think it's inappropriate to want to have an idea about your salary before accepting a position. After all it is a professional affair and you are entitled to know every little detail of the rights and responsibilities that come with the position you are considering.

I would however rather wait to see if they will offer the job to you, before taking up any negotiations. So in terms of priorities: 


make sure it's you who they pick
try to see what kind of an offer they would be willing to make.


And finally regarding postdoc salaries in Australia; according to this link they are around $75-$85K/year (that is aussie dollars btw). I have no idea how reliable this source is, but that was literally on the first page of a google search, so I am sure you can dig into it if you put in a bit of time on it.

Best of luck! :)