One way to hold this phrase: put the thing down in the middle of a market and let the buyers speak. Whatever they are willing to hand over is its market value. The owner does not set that number, and neither does the cost of making the thing. This is why the same object can be worth more today than yesterday without changing at all: the buyers changed.
Two branches
東西現在賣得到的價
這一支就是核心畫面本身，被估價的是看得到、摸得到的東西。
noun · B2
The amount of money that a thing such as a house, a car or a piece of land would sell for now, decided by what buyers are willing to pay for it rather than by what it cost to make, build or buy.
市價／市場價值
公司被市場估出來的總值
同一張圖，只是擺進市場的東西換成一整家公司，而市場換成股票市場。買家的意見變成股價，股價乘上股數就是市值。
noun · B2
The total value of a company worked out from the price of its shares, or the total value of all the shares on a stock market.
市值