We all understand "buy high, sell low" is a business basic. Even if we have no intention of selling for a profit, when we buy something which we know is worth a great deal more than we are paying, we are participating in this concept, if only in our imagination. I once bought a lovely etching for $85, hung it over my desk for four years and then sold it for the amazing amount of $1600 in Charleston - pretty much paid for my trip. I was thrilled and quite surprised at its value. In fact, I suspect I could have gotten a few hundred more if I had been willing to shop it around. What I DID NOT do, was go back to the seller and wave the $1515 under their nose.
There is nothing more irritating to me, as I clean up and catalog a new postcard to find that the card I have just paid $3 for was purchased by the dealer for 25p (that is about 40 cents!) I don't even want to calculate the mark-up which that represents. All I ask is that for this amazing profit, they at least do me the courtesy of taking 15 seconds to erase the price they paid from the back. Is that really asking too much?
I know, I know...Business is Business.