David Moyes admits Sunderland may have to sell Jordan Pickford at some stage, but insists it will take a potentially record breaking fee to let him go this summer.
Gianluigi Buffon's £33 million move from Parma to Juventus in 2001 remains the world record for a goalkeeper.
Everton have reportedly been preparing an opening bid of around £15 million but Moyes baulked at suggestions the Black Cats would be tempted to sell at that price.
Moyes was reluctant to discuss figures, but dismissed a suggestion of £20 million, confirming that a bid in the region of £30 million would be closer to what he would expect.
Moyes said: "I wouldn’t say any figure, but that [£20 million] would maybe get you one glove.
"I heard some disrespectful figures being bandied about. We don’t want to sell Jordan, but if we have to sometime on the journey, which sometimes you have to, to reinvest, it would have to take very big money."
Pickford's profile was raised yet again after one of his finest performances yet against Arsenal in midweek.
The Gunners racked up more than 30 shots in an one-sided contest but Pickford made a plethora of saves to limit the hosts to two second half goals. Arsene Wenger described his performance as 'exceptional' but insisted he did not need a goalkeeper in the summer.
Nevertheless the Black Cats are braced for bids from a number of other top clubs, who have scouted the 23-year-old extensively throughout his breakthrough season.
Everton, Manchester City, Manchester United and Liverpool could all potentially be on the look out for a goalkeeper this summer, though Jurgen Klopp earlier this campaign echoed Wenger's comments and said he was happy with what he has in that department.
Moyes said earlier in the week that he felt like a 'salesman' talking up Pickford's performances but is keen to pay tribute to the highlight of Sunderland's difficult campaign.
Pickford's performance against Arsenal was all the more impressive given it came after an uncharacteristic error days earlier against Swansea, the young stopper unable to reach Gylfi Sigurdsson's free-kick before Fernando Llorente turned home.
Moyes said: “I feel bad talking about him so much, but I think he has been the highlight and the positive we can really mention.
“For a young boy to break in and actually become an England international in as much as he was called up for the squad, Jordan has been excellent.
“His performance the other night was fantastic, it really was. Probably our biggest disappointment recently was the Swansea game, and Jordan was the one. I said on that day, it was nearly as if, 'Oh, Jordan's a made mistake!'.
“Jordan had probably been the only person who had hardly made a mistake the whole season, he had been so good. But the other night, everything was nearly perfect, his performance was so good – and we'll need him again this weekend, I've got to say.”