I get your meaning but at some point it is reasonable to take your own unpaid work into account.
My dad sometimes brags how he is able to save like 4€ on a grocery bag by going to a bunch of stores to compare prices and then going back to them to buy just the best deals. I mean that's great but it takes several hours to do so, so if he had spent an hour working instead he would have made up for it. Chasing deals is like an extremely low-paying job.