Economic transactions happen when both think it will benefit them - that is, when there are gains from trade on both sides. But that says nothing about the size of that gain. If you're a consumer, then the amount you value a consumer good minus the cost of the good is called the consumer surplus, and in principle it could be arbitrarily small. You could buy an apple for a dollar, which you value at a dollar and ten cents, and thus your consumer surplus would only be 10 cents.
My question is, what is the typical consumer surplus of consumers goods as a percentage of their price? If it varies by the type of consumer goods, I'd appreciate an answer giving percentages for different types of goods. Like groceries, clothing, cars, etc. Is there data on this?
I just want to get a rough idea of whether the percentage is typically low or high. I have a feeling that the percentage is a lot lower than most people would expect.