Just think how much money you spend maintaining your car vs. your own grocery bills, utilities, housing, and anything else. And in the Star Wars galaxy, think how much they've improved their machines, making them far more energy efficient. I'm sure they require upkeep, but I find it hard to believe they need as much as an actual human.
And I am glad for the inclusion of clones; I really wanted to see the clones too. I would have just done it differently.