Chelsea manager Roberto Di Matteo has said he will not pay more money than necessary to add to his squad after spending £60m on players this summer.
Di Matteo has brought in Oscar and Marko Marin, as well as brothers Eden and Thorgan Hazard, since the end of last season.
Chelsea are also trying to sign Wigan forward Victor Moses, but Di Matteo wants value for money.
"We're not going to pay over the top," Di Matteo said.
"What we think is the real value for a player, we have paid."
Chelsea have not officially disclosed the fees they have paid for any of their four summer signings, although Eden Hazard came in from Lille for a reported £32m, while Brazilian midfielder Oscar is understood to have cost £25m from Internacional.
Chelsea travel to Wigan on Sunday no closer to agreeing a fee for Moses.
Wigan chairman Dave Whelan this week accused Chelsea of "messing about" over the fee for Moses, warning the 21-year-old was going nowhere unless his demands were met.
Di Matteo refused to discuss the possible transfer, but said of Moses: "We've played against him before - we know very well what ability he has.
"He's a young, talented guy... that plays for Wigan."
Chelsea finished 25 points behind title winners Manchester City and runners-up Manchester United in the Premier League last season, and Di Matteo wants to close that gap.
He said: "We have to try, for sure. It's not that we're not going to try.
"We have to try to challenge ourselves with the other teams, so I wouldn't say there is no expectation."