Suppose that you value a hat from your favorite university at $20. The university bookstore has the hat on sale for $15. You purchase the hat but lose it on the way home. What should you do? Assume that losing the hat does not alter how you value it.
Go back to the bookstore and purchase another hat.
Wait until the cost of the hat falls to $15 or less before purchasing another hat.
Wait until the cost of the hat falls to $5 or less before purchasing another hat.
Do not purchase another hat regardless of the price.