The full-back is unsure the Tottenham star is worth the £100 million fee the Premier League side are demanding, before describing Lionel Messi as "the best player in the world"
Los Blancos are in talks with Spurs over a world-record bid for the winger, although manager Carlo Ancelotti has admitted the deal has stalled.
Alba, though admits he has not seen enough of the player in action to comment on the proposed €115m [£100m] figure Bale is commanding.
"If I'm honest, I haven't seen him play alot but I know he is a good footballer," Alba told Marca.
"In each case it depends on the needs of each team, what the club is willing to pay and what the other demands. Then time will tell if a player has been cheap or expensive."
Meanwhile, Alba has hailed Messi as "the best player in the world" following earlier claims by Blaugrana president Sandro Rosell that the Argentine ace would command a fee of around €580 million [£498m] should any club ever attempt to prize him away from Camp Nou.
"We're talking about the best player in the world. For us, he doesn't have a price. He is No.1. No player can stand up to him, and he'll continue being No.1 for as long as he wants," he added.
Alba also praised new coach Gerardo Martino for the way he has taken to the role in the Barca dugout, admitting he is happy to work under those who shun the limelight.
"Barcelona has always had calm coaches," he continued.
"We are happy with Tata Martino, as with Tito Vilanova. He is a quiet coach who only wants to talk about football and what happens on the pitch."
"I don't think we're going to change our style nor our way of playing very much. The truth is I like how we play."