That is not going be as easy for Liverpool FC as perhaps they would have hoped, as Chelsea FC have also shown interest in the player and are looking to add him to their squad. In fact, I wrote about this two weeks ago with Chelsea FC being one of the most serious contenders for the player, along with Fulham who were willing to offer up to 35 million euros to acquire the player. Valencia CF is demanding 40 million euros and with several premier league clubs vying for his signature there is no reason for Valencia CF to negotiate for the price.
Whoever reaches that number is going to acquire the player, though if he is to be sold, it's unclear how Valencia CF is going to cover his absence, considering Nico got injured recently and will be out for at least 3 months and additionally Samu Castillejo also got injured during last match and will be out for at least a month.
Yunus Musah has become more of a central midfielder, so we do sort of have cover for him, but he is very versatile and can cover multiple positions, which is part of his appeal, so it's going to be very hard to replace him, though maybe Valencia CF is waiting for exactly that to sell the player for 40 million euros and then purchase reinforcements!
Either way there are several premier league clubs interested in the player with Chelsea FC and Liverpool FC being closely linked to the player, though as I reported previously, we might even see Fulham and other teams come in the spotlight.
For 40 million euros I'd sell him, he is a solid player and has big potential, he's shown he can be very effective defensively, has a lot of speed as well, but for 40 million euros I think that is a fair price for him as of right now. There is no guarantee that he is going to become the next Silva or Aimar or Baraja for Valencia CF, so for 40 million euros I'd sell him.