The demand for the particular characteristics of the computer is the central aspect that determines the choice of the product. I want to buy a laptop of the same brand because the old one satisfied all my desires. Brand preference becomes the critical factor determining my demand for the new computer because other companies also provide gadgets with similar technical characteristics.
The notion of the willingness to pay supposes that there is a maximum price that the person is ready to pay for a particular product. My budget for the new computer is $1000, which is the limit I set for buying this product and the maximum price for it. The brand of the laptop I would like to buy is on sale for $850 in most shops due to the discount. As a result, the consumer surplus, in this case, is $150, which is the difference between the maximum price I am willing to pay for this product and its actual price. This difference in prices makes me feel that I make a good deal, and buy the computer I want for a lower price (Mankiw, 2018). At the same time, the marginal cost and the price the producer gets for the laptop are slightly different. In this case, the producer surplus is $150 because the store buys the computer I want for $700 and sells them for $850. The cost of the laptop is in the middle between the producer surplus and the consumer surplus.
The propositions on the market determine the willingness to sell this transaction. The sellers would not set the price for the computer lower than $700 because it is the price the producer sets. They need to profit from selling the product; thus, their price for this item is higher. At the same time, it is not practically justified for the seller to set the price higher than $850 because most shops propose this product at this price.
Reference
Mankiw, G. N. (2018). Principles of macroeconomics. Boston, MA: Cengage Learning.