> Like everything, it is always cheaper to do it (it being cooking at home, cleaning your home, fixing your own car, etc) yourself (if you don't include the cost of your own time doing the service you normally pay someone else for).

In a business context the "time is money" thing actually makes sense, because there's a reasonable likelihood that the business can put the time to a more profitable use in some other way. But in a personal context it makes no sense at all. Realistically, the time I spend cooking or cleaning was not going to earn me a dime no matter what else I did, therefore the opportunity cost is zero. And this is true for almost everyone out there.