I think a better way of thinking about this would be cost per user. How many hours a day do you spend doing the various errands around the house? If a robot was operating 16 hours a day how many households could it support? If we say it can make enough food to support 10 families a day and then in the remaining time do all the various chores spread over a week, the per household cost is 10k + electricity spread over X years. If a robot loan is 5 years like regular auto loans, it may be $2500 a year all considered