Per the source, Everton want to part ways with the Senegal international and Galatasaray are interested however, the Toffees want to recoup some of the €16 million transfer fee they invested in the striker last season.
Galatasaray who are currently serving a one-year European competition ban for FFP are reluctant to accept the buyout clause option being put forward.
A source close to the Lions has told Turkish-Football that Galatasaray want a lower buyout clause option in the range of €5-6m which would be within their budget.
Niasse was left out of the Everton pre-season squad and has been given the green light to leave. The 26-year-old striker is no stranger to Turkey having first made a name for himself at Akhisar.
Galatasaray were linked with Niasse before his move to Everton and he has revealed in the past that he would like to play for the Istanbul giants in the future.