"It's a significant amount of money and it's a huge outlay. "It may well stimulate the market now," Hughes told reporters.
"There is a lot of money out there now. The levels of money required now to attract the best players in the world is huge.
"Manchester United must feel it is good business for them. (manager) Sir Alex (Ferguson) makes key decisions very quickly and he must think it's the right thing for the club. You have to respect that," Hughes said.
The world record bid for Manchester United winger Ronaldo comes days after Real paid around 67 million euro for Brazilian Kaka, who turned down a move from AC Milan to Manchester City for a reported 100 million pounds in the January transfer window.
"I'm sure that they (Real Madrid) are very pleased with the business that they have been allowed to do, acquiring Kaka and the likelihood is that they have acquired Ronaldo too, Hughes said.
Hughes, who knows a thing or two about spending money after splashing out a British record of around 32.5 million pounds on Brazilian Robinho last year has been linked in the media with strikers Carlos Tevez of Manchester United and Valencia's David Villa.
"We are still looking to address areas of the team and squad but we have to make sure that the quality we attract here is the right quality," the former Manchester United player said.
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