His market value has risen accordingly at currently stands at around 25 to 30 million euros, which is only likely to grow through the rest of the season. Valencia CF has already put a price on him, but its reasonably above market value as to save face when they do sell him. Right now, Valencia CF is demanding 40 million euros for Yunus Musah and won't be listening to offers lower than that!
There are several English clubs already interested in Yunus Muash, one of the clubs that has shown the most interest in Fulham and they are willing to possibly shell out 35 million euros for the player or maybe sweeten the deal with money plus player if Valencia CF doesn't budge from their 40 million euros demand.
Valencia CF has no reason to lower the asking price though as Chelsea, Liverpool and Everton are all interested about the player and are inquiring about a possible purchase. There is big interest for the player right now and this means that Valencia CF are going to sell him by the summer, if not even sooner.