Even if we consider Liverpool as a rich team but they are not going to have Xabi Alonso easily. In fact, Xabi Alonso is not a cheap option for any team and even if we consider Real Madrid as a team that wants to hire Xabi Alonso we can understand that are some teams like Liverpool and Real Madrid, and even Bayern Munich they are all linked to thing Spanis coach which can make the transfer much harder because regardless of dealing with Leverkusen to make them accept this deal, they have to race with beasts like Real Madrid for Xabi Alonso.
However, can't be sure if Xabi Alonso can still have a good performance in Liverpool or not if he leaves Leverkusen.
Now Xabi could be one of the most expensive coaches if he wants to leave Leverkusen and certainly every club that wants his services must be prepared with that but when talking about the problem of the actual coach it will not be as expensive as the price of a player and surely Liverpool can bring him if there is an agreement between Xabi and Liverpool for next season.
Currently Xabi's release clause is only around 15 million but that can only be active if Xabi has one season left at Leverkusen but even so I think that as expensive as a coach it will not be the same as a player so that no matter how expensive Xabi it will not be more expensive than a player and anyone can still bring Xabi if there is an agreement including for Liverpool.