Everyone shops for things they need for themselves and for gifts for others. Imagine you are taking an online class and you are looking to buy a new computer because your old one died. Class starts in two days. The market for computers is very competitive. There are several brands that have similar characteristics such as storage capacity, processor speed, number of USB ports, etc. but you have owned one that you liked and you want to buy that same brand, the X-Mark.

You have a budget of $1,000. One popular store has the brand you like on sale for $850 because other stores are selling them for that price. You have a friend at that store who tells you that the store paid $700 for that computer.