Redknapp admits he would have loved to have bought the former Wolfsburg striker.
"The extra striker might have made a difference but I couldn't really see us getting anyone," Redknapp admitted.
"Everyone is talking about the centre-forward at Man City [Edin Dzeko] but if he's as good as everyone says he is then he now looks stinking cheap, doesn't he? I spoke to Steve McClaren - he said he's fantastic.
"I spoke to Van Bommel the other night - he said he's different class. I saw Jens Lehmann and he said he was the best striker in Germany by miles. And suddenly £27 million looks cheap, doesn't it, if he's that good? He and Tévez are going to be a handful."
Spurs made their own inquiry about Dzeko but Redknapp said the player's former club, Wolfsburg, wanted £50 million.
"He was too dear. And suddenly he looks cheap. Ronaldo doesn't look dear, at £80 million, does he? So how much is Messi worth - £1 billion?"