Ronaldo has again been linked with a summer move to Real, 12 months after the Manchester United winger was courted by the Spanish giants.
United remain confident the Portugal international will still be at the club next season, but Perez is tipped to make a big-money bid for the 24-year-old.
Reports have claimed former president Ramon Calderon had an agreement in place to bring Ronaldo to the Santiago Bernabeu - something Perez is unaware of.
However, at the start of his second spell as Real president, Perez is ready to splash the cash again after previously presiding over the 'Galacticos' era
"I don't know anything about the story of Cristiano Ronaldo. I only just took charge," he told television programme '59 segundos'. "But what I am sure of is that which seems expensive is the cheapest.
"In my last era the cheapest was (Zinedine) Zidane, who seemed very expensive because we paid 73million (euros) for him.
"Without knowing who we can get, there will be a massive effort for the great players of the world, because that is the Real Madrid model."
Competitive spiritPerez also laughed off suggestions that Ronaldo's temper could hinder him at the Bernabeu.
"I have not seen anything about him that would prohibit him from playing at Real Madrid," he added. "I have seen him get angry because he wants to win and (because of) his competitive spirit.
"The information I have on him says that he is an example on the pitch, a model."
Kaka has also been linked with a move to Real, but Perez denied rumours of a deal to sign the Brazilian, who has again pledged his future to AC Milan.
Perez added: "We started working today and we will lay the foundations to create a magnificent team.
"Kaka could be one of our objectives, but the prices the media are talking about are really out of the reality.
"Some things can last for days, others for months. We have time until August 31.
"It's not true that we have signed Kaka and I don't want there to be false hope. It's true that I have a great relationship with (AC Milan general manager, Adriano) Galliani, but there are other teams who have their own projects and everything has a price.
"Yes, I can say that I will work, but not everyone can come."