In the middle of a transfer window, it is easy for clubs to get carried away with the valuation of their players as the big boys of European football come calling.
Liverpool learnt that very harsh lesson in the winter of 2011 when they shelled out £35 million for Andy Carroll, only to see his value plummet over the space of 18 months.
The Reds aren't alone in making transfer mistakes either; after a poor season Fernando Torres' value has dropped dramatically since he signed on the dotted line for £50 million - although a decent campaign next time round will change that.
So with all the bluster of the final weeks of the transfer market still to come, how much are the Premier League's top players actually worth? And what is the most valuable asset each of the top club's have out there every week on the pitch? All the information you need to know is below! Figures courtesy of transfermarkt.co.uk.
Both Alex Song and Robin van Persie have been linked with moves away from Arsenal this summer, and carry a combined value of £50 million. (Getty Images)
Despite paying a record £50 million for Fernando Torres, his current value is just over £30 million, while Juan Mata's value has soared. (Getty Images)
Wayne Rooney is in a league of his own at Manchester United in terms of value, although the potential addition of Lucas Moura could change that. (Getty Images)
Sergio Aguero is worth his weight in gold after his title winning goal last season, while David Silva and Yaya Toure are both equally invaluable. (Getty Images)
Tottenham are holding out for a bid from Real Madrid for Luka Modric that represents his true value, while Kyle Walker's value will only rise with another successful season next time round. (Getty Images)
Andy Carroll's true market value was revealed with a bid of around £19 million from West Ham this summer while Liverpool would look to get their money back at the very least should Luis Suarez move on (Getty Images)