Cavani has been routinely linked with Chelsea and Manchester City this season, with Paris Saint-Germain also reported to be interested in the 26-year-old.
It was previously thought that the Uruguay international had a release fee much less than the figure quoted by the Naples club, but it now seems only an extraordinary bid will be enough to pull him away from the club.
"We included a very high buy-out clause in his contract because we want him to stay at Napoli," De Laurentiis told reporters. "The clause exists, though, and if some nutter is willing to pay 70 million euros for him, which would mean a net fee of 63 million euros for Napoli, we are ready to listen to the offer.
"However, let it be clear that the final decision lies with Edinson. He knows that he's respected here and that the people love him. Not just for his goals, but also because he's a serious and polite person."