Rossi is one of Europe's hottest properties and has been on Spurs' radar for some time. Redknapp attempted to bring the former Manchester United man to the club from Villarreal last term, but the club baulked at the reported £18 million fee.
The forward's stock, and asking price, has increased in the past 12 months but Redknapp has not been put off making a move - if the books can be balanced.
"I think Rossi is top drawer," Redknapp told Sky Sports News. "He's a clever player, he gets it into feet, holds the ball up and scores goals. He's the Italian centre forward now.
"We tried to get him last year - I think the fee last year was around £18 million. It looks cheap now. He is a player we nearly had last year."
Asked if the club would be willing to spend £30 million, Redknapp said: "I couldn't say, that's up to the club and Daniel [Levy, chairman]. But if you're going to buy top players they cost top money. They're not going to be cheap. It costs top wages and big transfer fees. You need miracles if you're going to keep picking players up for bargains.
"Everybody is looking for top strikers and they are at a premium. They are difficult to find."