Market price — the general price level or usual selling price for goods, currencies, stocks, etc.
この腕時計の相場はだいたい5万円前後だ。
The market price for this watch is roughly around 50,000 yen.
今、原油の相場が急に変動している。
Crude oil prices are fluctuating rapidly right now.
商品を買う前に相場を調べておくと安心だ。
It's reassuring to check the market price before buying a product.
Speculation — trading or betting on price movements (e.g., in stocks), engaging in market speculation.
彼は株で相場を張って大きな損を出した。
He speculated in stocks and suffered heavy losses.
相場で一獲千金を狙うのはリスクが高い。
Trying to make a fortune by speculating in the market is very risky.
Conventional estimation or reputation — the general opinion, common estimate, or conventional wisdom about something.
相場ではその作家は次の賞の有力候補と見られている。
By common opinion, that writer is considered a strong candidate for the next prize.
その時計は中古でも相場が高いので、売るときに有利だ。
That watch keeps a high resale value even used, so it's advantageous when selling.