Sane, who is valued at €100m by Manchester City, has been on Bayern Munich’s radar since last summer but a serious knee injury suffered at the start of the season scuppered any plans of a potential transfer.
Bayern Munich look set to revive their interest in the German international when the 2019/2020 season concludes.
Heynckes, who won four Bundesliga titles in two spells as Bayern Munich manager, is adamant Sane’s price tag has been blown out of proportion.
"He was in good shape before he injured himself so badly. For me, he has not yet made a breakthrough as an absolute top player," Heynckes told Welt am Sonntag.
"I think this is a player who is currently at a crossroads. Will he continue to work hard on himself, or will he continue to be just an extraordinary talent?"
"He has to be ready to take the next big step because there is no use in flashing the talent every now and then."
"I can honestly tell you that I don't think the price is justified."
Despite being voted as the 2017/2018 PFA Young Player of the Year, Sane surprisingly failed to make the cut for Germany’s travelling party to the 2018 FIFA World Cup in Russia.
Sane joined Manchester City from Schalke 04 in the summer of 2016 and has since won two Premier League titles with Pep Guardiola’s men.
