The Blues boss is adamant that there would be no need to offload players to balance the budget should he sign the Manchester United star, despite having bought already this summer
The Londoners are expected to make a renewed bid for the England striker after the Red Devils turned down their opening offer, despite the disgruntled forward being "hell bent" to leave Old Trafford.
"The club are working hard to keep the numbers in balance but we can still invest in a player who costs 20 million pounds, 25 million pounds, 30 million pounds and not break the balance," Mourinho told the press. "We don't need to sell to do that."
Asked if he could spend 50 million pounds on a striker, he added: "The striker I want doesn't cost 50 million pounds."
The Blues boss declared on Thursday that he was "calm" about his pursuit of the United forward, with a sizable stable of strikers at his disposal should the move not materialize.
Red Devils legend Paul Scholes, however, argues that it would be best for Rooney to stay put.
Mourinho has already added the likes of Andre Schurrle and Marco van Ginkel to his Chelsea squad this summer, with the England international his only remaining target.