FYI ... crop spraying in Australia is one of the most difficult and closed-shop employment fields of all, you'd have better luck with the airlines.
You'll struggle to get into "some" airlines, but a lot of them these days don't care so much since they don't invest a penny in your training. If you've got cash to burn then you'll probably get to play with some of the P2F lo-co's at least. Lucky you huh.
Failing that, certain turboprop operators actually prefer older individuals because they know they are less likely to run off to BA as soon as they get the golden phone call.
It's highly unlikely though that you'll ever get to recoup the investment you make - people have this idea that airline pilots make lots of money, which is actually bollocks until such time as they reach the left seat, but you'll need a number of years before you're ready for that. Obviously you can't get rich if you get your command at 55 and have compulsory retirement at 60
