Here’s another ethical issue and Jewish source response:

Case

Zelda and her mother love garage sales.  They are very good at finding real treasures among the junk.  One day they are hunting at a garage sale down the block. It is Dahlia and her mother’s garage sale.  Zelda and Dahlia are in the same class at school. Zelda and her mother find a vase on sale for seventy-five cents. Zelda’s mother knows that it is worth hundreds of dollars because it is a signed piece from an important porcelain designer.  The next day at school Zelda tells Dahlia in a nice, not a mean way, what a good buy the vase was. That afternoon Dahlia’s mother calls up Zelda’s mother and demands the vase back. She says to Zelda, “You cheated me and bought it way too cheaply.”  Zelda’s mother says, “I bought it at the price you asked.”  

What is fair and just here?

Answer

In Maimonides, The Laws of Acquisition, we learn:

[a] That both a buyer and seller must be honest in transactions.  Neither can cheat or defraud the other [12:1).

[b] Making more than a twenty percent profit on something is considered dishonest, and the laws of fraud say that the deal should be canceled or the difference (up to twenty percent) should be repaid (12:4).

[c] These rules of unfair profit apply only to necessities of life, things like food, clothing, etc.  When it comes to luxuries, a buyer and seller may charge and pay what they want (14:2). Porcelain vases are luxuries, so the deal is legal (if not fair).  Zelda’s mother can keep the vase (but Zelda may lose a friend).

Joel Grishaver, “You Be the Judge”, pgs. 91-92

Used with permission from Joel Grishaver