The median income for the census tract containing the Red Line Fullerton station is $100,341 - the highest of any Red Line station. The lowest median income on the Red Line is around the 47th Street station - $11,610.
Meanwhile, on the Brown Line, the high and low median incomes are at neighboring stations: $103, 609 at Chicago, and $13,185 at Sedgwick.
You can find these and other fascinating stats on the median incomes in the census tracts of all CTA rail stations at the Donkey Hottie blog. As the blogger notes: "In short, the graphs affirm most of what we already knew. Though I also was not expecting the Blue Line to be so much nicer between Western and Grand than it is in the Loop."
He even tried to explain the big dive in median income between Chicago and Sedgwick:
I can only guess that there’s a residual effect of Cabrini-Green’s ghost that’s pulling that number down. Even so, however, the Sedgwick census tract is bordered by North, Sedgwick, Division, and Larrabee, meaning that it’s one tract to the east of Cabrini-Green (which was west of Larrabee) and one tract to the north of the Frances Cabrini Homes, which are south of Division.
He devoted an entire post to the Sedgwick question.
Check it out. It's fun to at least see the median income at your rail stop.