What is the maximum willingness to pay?

Usually economists believe that increasing market supply tends to lower the market price; however, in the real market, supplier do not supply exactly the same product, and they tend to differentiate their products and many large companies tend to increase their revenues years by years. Therefore, the products in the market are not necessarily to compete with each other, and the market demand seems infinite.

The market demand is because the world population is large and some proportion of the population are not currently unable to afford products and are getting wealthier and going to be able to afford one in the future, it is also because these products are not permanent, they need upgrades or replacements frequently. To individuals, from my personal experience, I feel that our willingness to buy a product is not a strict conditional function that when it meets the condition, we buy the products, if it fails to meet certain conditions, we do not buy the products. Of course,if the price is over our budget (including our credit budget), we are unable to afford the product, so we will not buy it. However,if the price is within our budget, we may buy the product and we may not buy the product. People argue that then the decisions of buying or not buying the product merely depend on the utility it gives to us.However, utility is something that we cannot have exact and accurate valuations. Therefore, I think the decision of whether or not the buy an affordable product is a distribution of probability.

For affordable goods or services:

The market price locates in the area where is the variation of probability is the largest, as the market price can send strong signals to individuals and influence their valuations of the product.

For unaffordable good or services:

The probability is 100% until the price exceed the budge, this is because this product is unaffordable, which means the market price is greater than the budget, if the individual is able to buy the product with its budget and resell it in the market, this individual can gain profits.