They include Juan Vargas, Michael Carrick, Argentina international Juan Pablo Sorin and, most recently, his countryman Jonas Gutierrez.
Redknapp told The News: "I would have taken Jonas Gutierrez for the money he cost Newcastle.
"We offered 8m Euros for him in January. He ended up going for 2m Euros.
"I don't know how that happened. I haven't got a clue how that worked out.
"I was surprised when he moved. I couldn't believe it when I was told the fee.
"There's a court case pending I understand. That's the problem.
"He is still part owned by his old club in Argentina and Mallorca. I think the two clubs want more for him than what they got.
"I don't know how that will work out.
"I liked him, though. He's a very good player.
"I think he paid up the last year of his contract, but I suppose Newcastle will look after him in that respect by paying him up.
"But he's a good player, very good. He got in the Argentina team. He's a brilliant talent.
"There's a lad in Italy, Juan Vargas, who has just move for 16m Euros.
"I had him over for three days last year. They wanted about a million or so.
"I liked him but he went to Italy.
"It's hard. He wouldn't play in any games and I just had him in for training, where it is hard to judge a player.
"You win some and you lose some.
"Juan Pablo Sorin has just been released by Hamburg. I had a bad day with him once.
"I got him to London with me and Milan Mandaric, when he owned the club.
"He came all the way over to meet us, but Milan didn't want to spend the money in the end.
"Michael Carrick was another one. We could have had him for £2.5m.
"He was on his way down for a medical.
"But in the end we didn't pay the money."