Long way to travel mate. I think you'll have more luck exchanging Euros or sterling than oz dollars. There are plenty of banks in Bansko itself where you can change while you're in resort and also ATMs to make withdraws if you run short.
After been to Bansko and if I was travling from down under, I'd personally change my currency into Euros or GB£ and then change into Lev when I got to the resort.
Hi, Todd!
Did you visit Australian Open?
Exchanging rate between Euro and Lev is fixed in Bulgaria. It's about 1.955 levs for 1 Euro in banks. It's better to exchange your money in banks. I don't know exchanging rate between euro and australian dollars but I guess you know it and you can calculate what is better for you.
Have a great holliday!