Being a visitor and then staying illegally is one way, but it doesn't sound very luxurious.
Alright so they'll have to get a passport.
Then travel to australia.
Maybe go to some type of fund raiser and make a huge donation. Get the attention of the right people.. and then find a way to have a permanent visa through them.
Is that a realistic plan?
Any other ideas?
Lets assume I can smuggle the money somehow.
Most of it isn't paper money, it's rare coins. Some are worth 10 million each.
People worth a 100 million have offshore accounts to hide / transfer wealth.
The world of offshore IBC's (international business corporations) hasn't seen a lot of exposure in films, but I think it could work very well.
Most companies that assist in setting up these offshore companies are located in inconspicous office buildings without any signage, featuring generic office workers while catering to an extremely wealthy clientele. These companies sometimes also assist in applying for Visa's and such. The contrast between the boring lives and the paper-pushing accountants and low-level lawyers and their clients could be an interesting addition.
There's also some interesting restrictions that you can put on the money through these constructions.
In a much-used construction by the offshore community for example, the wealthy guy invests 10$ million in a company he sets up in a tax haven, officially this company invests in real estate. In most tax havens, companies are not required to name their owners, so nobody knows that he owns it.
Next, the company buys a house in Australia (say, as an investment), and rents it to the wealthy guy at a bizarro low price. Next, the company can pay his CEO (again, the same guy, but undisclosed, ofcourse) a good sum of money for making such a good investment.
This way you restrict the direct access to 100Million cash, and give your character, despite being extremely rich, the option to run out of cash in the short term, which could increase tension.