You can use the 'Transfer Compare' button in order to see what a similar player has recently been sold for on the market.
There is some debate over the usefulness of Transfer Compare, as some people feel is does not price players with any great accuracy. The main accusation is that it does not accurately account for the value of secondary skills. Many believe winger comparisons are particularly badly served; wing, playmaking, stamina, passing and defence skill are all used by transfer compare to set a price. Others see Transfer Compare as an inhibitor of the Hattrickeconomy, by reducing prices.
Others see Transfer Compare as a boon to new players, in that it allows them to see roughly how much their players should be worth, and how much a potential player should be purchased for. Still others see Transfer Compare as one tool to reduce the effectiveness of daytrading.