Pep Guardiola admits Manchester City's £200million overhaul is unsustainable and it will not be repeated in future transfer windows.
City have splashed out on Ederson, Bernardo Silva, Kyle Walker, Benjamin Mendy and Danilo as Guardiola plots an improvement on the first trophyless campaign of his coaching career.
Kylian Mbappe was linked with a move to the Etihad Stadium, but Paris Saint-Germain and Real Madrid have taken up the running in the chase of Monaco's France international star.
City's spending is a part of an explosion of fees, with PSG forking out a world-record €222m to sign Neymar from Barcelona, but Guardiola believes the bubble will soon burst.
"I think it is unsustainable," Guardiola said. "Sooner or later it's going to finish.
"For example, hopefully next season I will be here and we are not going to spend how we spent this season. Six players were out of contract. In the last six or seven years Manchester City didn't buy full backs. We didn't have full-backs and you have to buy full-backs.
"We bought three and the market is so demanding for all the teams, not just Manchester City.
"It started with Real Madrid and Ronaldo going for £80million and then Bale for £85million and everything went more expensive. Now with Neymar.
"But it is going to finish, it is unsustainable. In the next three or four years Manchester City will buy one, two, maybe three players. But not what happened this summer.
"We needed to do that because it was one of the oldest teams in Europe, not just the Premier League, and we needed to change it. We were not able with those players to find a solution. But the solution is not changing players every season."
Guardiola again pointed to a defensive example in his examination of inflated fees in the current climate, suggesting a younger Dani Alves would command a fee similar to that which City paid for Walker and Mendy.
He added: "A few years ago, Spain used to have the most expensive signings, now PSG has made a great signing with Neymar. This is relative.
"I remember signing Alves for €37million, everyone thought that was crazy.
"That is the equivalent of 50-55 million now, but Alves was one of the best full-backs in Barcelona's history. Three or four players will never be expensive because of what they will give you."
