Caporegime
You say West Ham won't walk away but they're not going to pay over and above what they think is reasonable
This is the key part. What they think is reasonable. Not "what we think reflects his situation at United". Of course they will try to lowball us, why wouldn't you. If they are happy to pay £25m for him they aren't going to walk away if United want £25m simply because they think United are desperate. They won't cut off their nose to spite their face.