How much does the travel actually cost? Let's say $250 a head return (probably cheaper with their deals with Virgin, etc, but seems a reasonable estimate). You're probably flying what, 30 people? 22 Players, travelling emergency and 6-7 coaching/support staff? Let's be safe and say 32? $8000 per team, you might have what, 8 travelling interstate any given round? Throw in a nights accommodation at $100 a head, 22 rounds a year and you're looking at $1.9 million per year. That's about what Gil gets paid in a normal year.
I really don't know why they don't just create a national reserves competition. They're already halfway there. Becomes easier to package the rights and sell it too which would easily account for the cost. No one probably cares watching if it's the Collingwood reserves vs Southport, but if you have Collingwood Reserves vs Carlton Reserves you'll get a few eyeballs.
Just leave the state leagues to their own devices.
You're kidding yourself if you think the TV rights to a reserves comp are worth anything. You'd be lucky to get any TV coverage at all but for curtain raiser games where the TV gear is already in place.
Your airfare estimate is grossly under as well. Players don't fly on special 90 day advance sale fares.