It's fine for Everton/Martinez to be happy with rejecting a £38m bid - but - that will put a lot of faith into the mentality of both Baines and Fellaini.
As much as they might not like to admit it, Everton are not a CL club and will not be a CL club anytime soon. Modern football's a bitch etc.
Fellaini and Baines are both good players, bought by Everton, who are probably not going to get a great number of opportunities to play at the very highest level. (Baines in particular at his age)
So if Everton take the stance that they will not sell their players to top European clubs on principle - that's totally fine. But don't be surprised if the next Fellaini chooses not to come to Everton because he knows that he can't use it as a stepping stone to further his career.
I hate that it is how modern football works, but it is the reality of the situation.
I think £40m for those two is highway robbery, and hope we'll say f*ck it at this point. See how Everton get on with Fellaini and his agent knowing Everton rejected a value above his previous release cause, and are preventing him from joining a CL club at the peak of his career.