The 23-year-old has told the club that he wants to leave in January.
Podolski has been linked with Everton, Tottenham and Manchester City in recent weeks.
“Everything in life has its price,” Beckenbauer told Bild.
“Two and a half years ago, we paid €10m (£8.4m). Now, the fee is €15m (£13m).
“You cannot keep a professional if he is unhappy, on the bench and not playing.
“Poldi does not quite fit into our way of playing. He is a top-class striker when he has space in front of him as he has the pace to run clear.
“But the teams we play against are usually very defensive, so we need players who can get into the penalty area – Miroslav Klose and Luca Toni in particular.”
