Spurs signed forward Brennan Johnson for 50 million pounds and midfielder James Maddison for 40 million pounds in the Australian manager's first transfer window last year. In January, they brought in forward Timo Werner on loan and defender Radu Dragusin.
Spurs have signed 10 players under Postecoglou so far and are expected to make more deals in the close season after signing 18-year-old Swedish midfielder Lucas Bergvall last month, who joins them in July.
"I don't think we're anywhere near where we want to be. It probably will take a little bit more than three (transfer) windows to get there for sure," Postecoglou told reporters on Friday.
"I don't think we are in a position to spend 100 million pounds on a player. That is not the case and I don't think it will ever be the case for the club.
"Our competitors are (spending), irrespective of the positions (they are in)...I have always felt with those things it is not what you spend, it is how you spend it."
Chelsea, who are 11th in the standings, spent 115 million pounds on midfielder Moises Caicedo in last year's close season, eclipsing the record 106 million pound fee they paid to sign midfielder Enzo Fernandez in January 2023.
Asked why the Spurs would not spend as much as their competitors, Postecoglou said: "It is purely financial. If I had the luxury of 100 million pounds, I would rather get two 50 million pounds players."
Postecoglou's side trail fourth-placed Villa by five points with a Champions League spot on the line but have a game in hand.
