There are lots of things that I can afford but choose not to buy. It doesn't mean that no effort went into producing them, it means that their value to me is lower than their cost.
I agree. And then you even forget the opportunity costs. Even if the value of the "thing" you're considering buying is larger than its cost, you can only spend the money once. Thus, you buy the "thing" that has the highest value for the price you pay.