Arsenal are demanding at least £8m for Folarin Balogun.
Brentford have made an approach for the 19-year-old forward, who has a year remaining on his contract at the Emirates Stadium.
Balogun has not made a first-team appearance but Arsenal have nevertheless indicated they want a sizeable transfer fee in order to let him go this summer.
The price will not necessarily deter Brentford if they win promotion to the Premier League – they face Fulham in an all west London play-off final on Tuesday for a place in the top flight.
Brentford were keen to sign Balogun and striker Ivan Toney during the January transfer window but were unable to agree deals for either player.
Talks have resumed with Peterborough over striker Toney, who has scored 26 goals for the League One side this season.