Redknapp insisted Spurs must hold on to their star players if they are to remain a club challenging for European honours.
He said: "Once you start selling one, it sends out the wrong signals. 'Manchester United sold Ronaldo but they got an offer of £80m so in the end it was good business. But we wouldn't want to sell a player like Gareth Bale at this time, when we're trying to build the club.
'It would have to be that type of figure. It would be an amazing figure if you ever sold him. But how do you replace a player like that? Once you start selling off your prized assets - I had it at West Ham.
"We let Rio Ferdinand and Frank Lampard go and then Joe Cole and the rest followed. If you are looking to build a club, you can't be selling Gareth as then Luka Modric wants to go and someone else wants to go. Then you end up where Tottenham were for four or five years, finishing half way up the table each season."