That is what kills contractors and subs alike,getting payed.On the job dealing with change orders," I'll sign make the change" then you'r in court lucky to get a dime on the dollar.Many guys have tried to hang thier own shingle and air out houses.You put in the equipment the homeowner won't pay.Can't remove equipment [laws on their side] and you lose you'r ass.Big job small job same game,only some big guys can wait it out.Little guys gets wiped out.Worked for an out of town contractor that had been in bussiness for over 100 yrs. only to close the doors because they could not get payed.Many want to work for the city/government juciy contract.Downside is waiting for payment.