The 20-year-old was recently named Brazil's Young Player of the Year and has been likened to former Milan idol Ricky Kaka.
Sabatino Durante told calciomercato.com: "There is concrete interest in the player and Milan have seen him many times. But I believe that Milan must first look at their budget. The Milan of three or four years ago would have probably signed Ganso in two minutes.
"Ganso's valuation is reasonable. The President of Santos is asking for 25m. This is the demand. Ganso likes Milan a lot.
"For a Brazilian speaking about Milan is like speaking about home because of the many Brazilians who have been at Milan. But this does not mean he can't move to other teams.
"I heard from Adriano Galliani 10 days ago but for other situations. It's a deal that has yet to be put on the table."