Your "basic" level player i.e. joe average is 3 stars . but it all comes down to what level league you are in.
you could be in a level league ... say level 6 ( random ) where the average
3 star player is level 40-44 ...
a 4 star player 45-49
and 5 star 50-54.
Now .... the maximum you can see in transfer market is 2 stars above average ( 5 stars ) , which normally means 2 leagues above where you are. But the 5 star player you see will only be a 3 star player to a player 2 leagues above you as that's his "average"