They don't always; like anything else, it depends on the circumstances. If it comes to Liverpool risking being in the same situation as last season then they would probably accept say £47 million as opposed to holding out for £50 million.
If a player makes it emphatically clear they want to leave and for one particular club, it does weaken their ability to say, no we want £55 million.
if we buy suarez, bernard and fellani, we will have a strong enough squad to compete
Man city's new signings might not adapt to the EPL
Man united may collapse under moyes, they've lost 2 out of their first 3 pre season games
Chelsea may fuck up due to moriniho's wumming
all in all is also important to take note that this season's premier league will have the highest dispersed amount of talent ever.
they might not want to sell, but these days if a player puts a transfer request in, or releases a statement etc more often then not, player power wins. if he puts in a transfer request, ive read he gives up a 5million pound loyatly bonus or signing on fee or whatever it is, we add on 5 million in add ons about trophies won. deal is worth 50 million to liverpool potentially and a guarenteed 45 million.
take a look at last year, we didnt want to sell van persie, he released that statement, he left. same thing can happen to liverpool. but in this day, bidding 40 milion pounds is a serious bid. if arsenal wanted to bid just to say to fans we tried, they would bid 35 million max.
Tevez wanted to leave Man City though, he didn't until they wanted to let him. If Liverpool don't get their money they are under no obligation to sell, it really depends on how they want to manage this.
In addition they can try and get other clubs involved by brokering exchange deals perhaps.