Michael Carrick has urged Manchester United to splash the cash to keep pace with their Premier League title rivals.
United have spent around £85 million on Andrey Santos, Youri Tielemans and Karl Darlow since the end of last season.
But that outlay pales in comparison to some of United's fellow title contenders, with Manchester City, Arsenal and Chelsea all paying huge fees for high-profile signings.
Carrick knows United need more quality and depth if they are to challenge for a first English title since 2013, while also competing in the Champions League.
Remarkably, United have never spent more than £89.5 million on a single player – the fee paid for Paul Pogba in 2016.
And ahead of his first season as permanent United boss after a successful interim spell last term, Carrick called on the club's hierarchy to push for more new recruits.
"I think we've done really good business and we've got really some top, top, top players," Carrick told reporters on Thursday.
"We're delighted with that. We always want to improve. We want more, we need more, we keep looking for how we can do that. That never stops."
Carrick led United to a third-place finish in the Premier League after he replaced the sacked Ruben Amorim.
But with United so far spending less than promoted sides Coventry and Ipswich, some fans are becoming restless as their Premier League opener at Hull on August 22 looms into view.
"Money's money, I get that. It's still about the football, and that's where the competition lies," Carrick said.
"Certainly the situation is what it is as well, whether that's finances or whatever. For now, we've got to make the most of it, but we've got to keep pushing and push everything and every boundary that we can to be able to win again."
Asked why United were not spending on the level of other clubs, Carrick added: "To be honest, I haven't got the answers for that. We're working with pushing everything that we can to make the best of it."
Having spent last season on loan with Barcelona, Marcus Rashford is back at United this week after returning from the World Cup.
Barcelona declined their option to buy the 28-year-old England forward and questions remain over his United future.
"He's our player, and he's a good player and he gives us something a little bit different in the group," he said.
"Marcus can offer us so much. He has done, and he can do again, so in that respect it's quite exciting."
Several United players have backed the team to dethrone Arsenal as champions and the understated Carrick wouldn't rule out a title push.
"We've definitely got the potential to achieve something really special," he said.
"I'm not hiding from the fact, and we should aim to do that, but I can't give you a definite answer on that.
"It's certainly what we're pushing to do because we have to, because that's the club we are."