Heerenveen director Yme Kuiper insists the club will not let midfielder Michael Bradley leave on the cheap.
Bradley will return to the club on Friday after playing for the United States at the Olympics in Beijing.
The 21-year-old is looking for a transfer and has refused to sign an extension to his current contract, which expires in June 2009.
"Bradley is allowed to leave us, but only for a realistic transfer fee," Kuiper told the club's official website.
"If that does not come along, it is better that he stays with us. Bradley is a good football player who can certainly be of value to us."
Middlesbrough, Blackburn and Everton have all be strongly linked with the American throughout the summer, while a number of German clubs, including Hamburg, are also said to be interested.