Ribery is targeted by a host of European giants and Bayern are already in the fight to keep the French international.
"If I hear that there was an offer for 125 million Euros for Kaka, then Ribery has a market value of at least 100 million," Hoeness told Bild.
Kaka was on the verge of a 125 million Euros move to Manchester City in January, before the Brazilian made a u-turn to snub City's money and stay at AC Milan.
Real Interest
Former Real Madrid legend Zinedine Zidane earlier said that he wants to bring Ribery to the club if the former becomes Los Merengues' football director.
The former World player of the year confirmed that Real will do whatever it takes to lure Ribery from Bayern.
Zidane is expected to land the director post if Florentino Perez wins Real's upcoming presidential elections.