I don't know if you can buy a new combine & head/heads for less than $500000.  1/3 for machine ,1/3 for fuel/repairs, 1/3 for labor.   25000-30000 acres to make the numbers work @ $50 a acre ..  I figure it costs me close to $75 a acre to own and support my machines.    But I get paid by the pound, not per acre.   I don't look for extra work.   But a lot of people are willing to work for experience ,And for the right to be called a farmer will work cheap .   I have 60 years experience,  got enough experience , I'm in it for the money now.