Castaignos endured a difficult time following his move to Eintracht Frankfurt last season and it is widely thought that the German side are looking to get rid of the attacker this summer.
Despite his struggles, Castaignos has been attracting the interest from a number of clubs and recently, it was claimed that the Premier League duo of Newcastle United and Southampton were interested in the 23-year-old (The Chronicle).
Now Portuguese news outlet A Bola have gone on to provide an update to the transfer status of Castaignos and have claimed that Frankfurt have set an asking price of around £4.3 million for the former Inter Milan man.
The report adds that Portuguese giants Sporting Lisbon are also interested in signing the Dutchman and have already placed an offer on the table for Frankfurt to consider.
Both Newcastle and Southampton have the financial capability to match Frankfurt’s asking price for Castaignos but they will have to move quickly due to Sporting’s concrete bid.