Here’s another ethical issue and Jewish source response:

Case

It is Sunday afternoon and Bob is working on a new plastic model kit of one of the star cruisers from Star Wars.  In the middle of the work he runs out of glue. He tears his room apart and finds that this was his last tube. He gets on his bike and rides to Geoff’s house.  Geoff has a whole box of tubes. Geoff says to Bob, “Because I like you, I’ll do you a favor. I’ll sell you a $1.79 tube for $5. Otherwise, you can wait until the model shop opens again on Monday.”  Bob says, “It’s robbery, but I’ll pay for it.” He takes the tube and finishes the model. Later, his older brother tells him it was robbery. The two of them go and demand that Geoff return $3. Geoff says, “You knew what I was doing.  You agreed. A deal is a deal.”

Answer

Geoff overcharged Bob for a tube of glue he really wanted.  Now Bob wants Geoff to refund the overcharge.

[a] In the Talmud there is a category called ona’ah moneh that covers overcharging.  There are two basic rules: (1) You cannot charge more than twenty percent of the “regular” price of something without telling the buyer about the overcharge.  (2) You can never charge more than twenty percent over the usual price of basic necessities (bread, eggs, milk, grain, etc.) (Bava Metzia 49b).

So normally Geoff would be able to keep the profit, because he made the price difference clear to Bob.

[b] Bava Kamma 115a tells the story of a guy who was escaping from Roman soldiers and so agreed to pay a ferry pilot three times the normal price to take him over the river in order to escape.  Later the rabbis made the ferry pilot return the excess fare (because he was taking advantage of the situation).  

[c] Rabbi Joel Sirkes (1561-1640) applied that text to the case of a businessman who intentionally paid too much for goods in order to complete a shipment.  Later he, too, took the matter to court and got everything past the twenty percent extra profit back – even though he had agreed to the price at the time.

He got his money back, and so should Bob.

 Joel Grishaver, “You Be the Judge”, pgs. 37-38

Used with permission from Joel Grishaver