But they have not given up hopes of getting a deal done and recent history with Harry Maguire and Bruno Fernandes suggests they could meet the asking price further down the line as the deadline nears.
The Red Devils need to sell to fund a move for Sancho and will consider offers for six players.
It is understood that Chris Smalling, Marcos Rojo, Andreas Pereira, Jesse Lingard, Diogo Dalot and Phil Jones are all for sale for the right price this summer.
Smalling and Rojo have both spent the year out on loan and United will hope deals can be reached to make their exits permanent.
Pereira and Lingard have both fallen down the pecking order since January after the arrival of Bruno Fernandes and look likely to be surplus to requirements.
Jones and Dalot have also barely featured, with Timothy Fosu-Mensah reintroduced ahead of Dalot in the latter stages of the season as cover for Aaron Wan-Bissaka.
United were knocked out of the Europa League at the semi-final stage on Sunday night, and club legend Paul Scholes immediately warned Ed Woodward he needs to be ready to spend big on marquee players if they are to win trophies again.
Scholes told BT Sport: “I thought they were really good tonight against a really good Sevilla team, but that 15-20 minutes after half-time, with all those chances, you’ve got to score them.
“You talk about quality, talk about spending money on centre forwards and wide players.
“You talk about hundreds of millions for those players, but those are the players that win you trophies, the ones that win you medals.
“We know all this Sancho thing is going on, but they need to start spending the money. If they want to win trophies, they’ve got to start spending the money.
“OK, they’ve created chances tonight but if you think a Sancho is in that team tonight I think United are scoring.”