The Australia international has failed to establish himself as a regular in the first team and has been linked with a move to join fellow internationals Harry Kewell and Lucas Neill at Turkish giants Galatasaray.
Allardyce did, however, comment that he was not looking to sell any of his current squad, with Rovers currently undergoing a transitional period in the boardroom as they look for investment.
But with the club looking to possibly raise funds, Allardyce could be tempted by a significant offer for any of his players.
"It depends like anything, Blackburn Rovers will ultimately sell anybody if the price is right because we're a selling football club," Allardyce said.
"We sold players last year to the tune of £33million, but we don't have to do that now so unless the right price and it's good for the club, we won't be looking at it."
Grella has been hit by injuries in England since moving to Ewood Park from Torino in 2008, but Allardyce is confident he could play more games should he stay at the club.
"He's been working very hard on a programme on his own," he said.
"We hope he's over that now, he's back here fit again and we hope he shows the sort of form he showed in Italy."