Jurgen Klopp believes Borussia Dortmund got a bargain when they re-signed Marco Reus from Borussia Monchengladbach.
The Bundesliga champions paid the release clause of €17.5 million for the Germany international winger and he agreed to join his boyhood club towards the end of last season.
"If we had signed Reus any later, he would have cost much more," Klopp told Bild. "We got him cheap, even if it was still for €17.5 million.
"His market value is honestly much higher than we paid for him, but it's not as if he feels any pressure. In fact, he doesn't seem to care - and neither do I."
Dortmund, who also beat Bayern in the DFB-Pokal as the Bavarians finished trophyless for a second successive season, know they must see off a strong challenge from Munich if they are to retain their title.
Bayern have brought in a number of players including Mario Manduzkic and Claudio Pizarro, but Klopp said: "Bayern Munich's transfer campaign is only natural.
"They are seizing every opportunity to reinforce, as are we and the likes of Borussia Monchengladbach, Schalke and Bayer Leverkusen.
"The market is not closed yet, but Gladbach have invested fantastically, while Schalke had a very strong team last season. As always, they will mount a close fight for the title in addition to us and Bayern."
Dortmund have also brought Julien Schieber and Leonardo Bittencourt to the club this summer.