Chelsea had £20million bid for Stones rejected by Everton last week, with Roberto Martinez criticising the Premier League champions for the way they handled their approach.
Unperturbed, the west Londoners are expected to up their offer for the 21-year-old, who they view as a long-term successor to John Terry, but Mourinho knows Everton will not let him go without a fight.
“That is the market now,” Mourinho said.
“You only pay it if you want to. If you don’t want to pay it, don’t pay. It’s as simple as that.
“The market has no rules or limits from season to season.”
After the summer departures of Sylvain Distin and Antolin Alcaraz, Everton’s defensive numbers are already on the light side, but Mourinho, who has risked further upsetting the Merseysiders with a “smaller club” comment, is determined to test their resolve over Stones.
“It’s a good market. That’s why smaller clubs, if they have interesting young English players, they use that in the right way for them,” he said.
“I don’t criticise them. They play the market for themselves. If the big clubs don’t want to go over certain limits, they have to make a decision.”