Cesar is likely to leave Loftus Road after they were relegated from the Premier League, but Redknapp has insisted that it will take a good offer for the club to part ways with the Brazilian international.
The former Tottenham Hotspur boss told reporters: "He's a top, top goalkeeper. There's no doubt about that. He's a Brazil international so for him to play in the Championship next year would be difficult. I can understand that.
"But he's a good goalkeeper. It would take a good offer. How this game works is you buy players and those who don't do well, you're stuck with them but those who do well, they think they'll walk away for nothing.
"You've got to get what you feel is value for him. He's going to cost decent money if anyone wants to buy him. He's a good goalkeeper."
Cesar's agent Josias Cardoso claimed on Thursday that the former Inter Milan stopper would likely remain in Europe should he leave QPR.