Qantas doesn't make any money out of their cadetship. Others like Sharp do make a profit from the flight training (no more than usual schools) and almost certainly save money on FO pay. Then there is J* which is the immoral, probably dangerous, referred to above.
Either way they cost a lot, have no guarantees (the 'lucky' ranges from 90% to ??) and generally aren't as flexible in terms of study (they are course you are on rather than the more modular form of usual flight schools).
There are big threads out there on each of the cadetships you can look over anyhow and make your choice.
I am assuming you have looked at the ADF and discounted it, if not give it a look!