The former West Ham striker believes that the Hammers will need to sign a striker following the injury to Enner Valencia.
The Ecuador international has been ruled out for 10 to 12 weeks with ankle and knee injuries, which means that the Hammers will want to replace him.
Hartson believes that the Premier League outfit may have to pay inflated price for a striker, as clubs will know how desperate they are.
“Valencia is a top class player and was brilliant last year so they will need to get someone in quickly to replace him,” the 40-year-old wrote on Kicca.com.
“The problem is other clubs will now know that West Ham are desperate for a replacement so, not surprisingly, the price for strikers will shoot hugely upwards.”
Valencia is one of the better players in the current West Ham squad and will be key in their aim to finish in the top eight of the Premier League this season.
The 2014 summer signing was one of the Hammers’ best players during the 2014-15 campaign.
The former Emelec forward scored four goals and created 17 chances in 32 Premier League appearances for the London outfit last season.