How much would your small business need to grow to be able to commission art for $30 000 to cover the five main RMU books?
I don't know where you are getting that figure. $3,000 would probably get you nice covers for all five books; for twice that, you would have your pick of artists.
I simply took your suggested art budget of $6000 for a book and multiplied by 5 to cover all the books. It is a lot of money and I am still curious how much your business would need to grow to support such large investment. My hunch is that you don't answer despite your bold words since making a major roleplaying game is whole different ballpark from your style of publishing.
Why should we at all assume they could predict such sales?
Well, if you run a Kickstarter, it's a cinch.
Maybe...they would have known how much money they could devote for art, but on the negative side of running a kickstarter is that it would raise demands on very different release schedule. Ironcrowns release pace for RMU is something that would generate lots of bad blood in a kickstarter situation. Without a kickstarter we can be sorry it is so slow, but not make any real complaints.
Of course, if the kickstarter had given enough money to be able to pay the freelancers to skip their daytime job the release schedule could be made much more user friendly but that requires a very different scale of money. Essentially it require hiring the freelancers as full time employee, but only for a very limited time. If the person is really sure they can get their old job back afterward, they might consider it but myself I would require lots more than $100 each hour even complement to accept such offer.