That would make the 21-year-old a much more attractive target for Arsenal and City, and potentially other top clubs, as his current price is unrealistic.
Gaya is a hugely talented prospect but has been part of a Valencia defence in 2016-17 that has conceded 61 goals in 35 La Liga games.
It is highly unlikely the Gunners would be prepared to shell out more than £40 million for him, but for £25 million he could be a fine addition to Arsenal's squad.
Spaniard Gaya is adept both defensively and going forward and could be a fine successor for 31-year-old Nacho Monreal on the left of Arsenal's defence.
According to Bild (via football writer Kristian Sturt), Arsenal could add Schalke left-back Sead Kolasinac to their squad in the summer:
But that would not necessarily rule out them moving for Gaya next year, as both Monreal and Kieran Gibbs could be on their way out of the Emirates Stadium and Arsenal need depth across the pitch, per Jeremy Wilson in the Telegraph.
Meanwhile, Arsenal scouts reportedly watched 19-year-old Amine Harit play for Nantes in their recent Ligue 1 clash with Lorient, according to Foot Mercato (via Get French Football News).
The French attacking midfielder has made 28 league appearances for mid-table Nantes in 2016-17, scoring one goal, per WhoScored.com.
Harit needs to improve his finishing, but he clearly has talent and boasts genuine attacking flair, as can be seen below:
Arsenal manager Arsene Wenger has a history of signing young French talents, so it would be little surprise were he interested in Harit.