We try to make an occasional dent in the amount of junk in our house. It makes for a handful of decent experiments in everyday economics. Today, I shipped a box of about 3200 sports cards that I sold on eBay for $5.50 with $0 shipping. They cost over $13 to ship, and processing the echeck with PayPal cost $0.46.
Naturally, they raise two questions: 1. Have I done something nefarious by selling a bunch of cards for a fraction of what I paid for them? 2. Was I just ripped off because I didn’t at least recover the costs of what I paid for them (or even the cost of shipping them)? The answer in both cases is “no” because the relevant cost isn’t what I paid for them. That simply can’t be recovered. The relevant cost is the next-best alternative use of my time, my energy, and the cards. The fact that I lost money (the value of my time notwithstanding) suggests that they weren’t worth much—indeed, no longer worth what I paid for them years ago.