Cards aren't really where it's at anymore. It appears that they're making a comeback, but memorabilia is still the mainstay of sports collectibles. You can sell some of the complete sets from the 70s/80s/early 90s for $250-$500 but it really depends on the series (Topps, Donruss, Fleer, etc.) and what rookie cards were a part of that set.
Memorabilia can't be beat though. It's so much more presentable for the sake of display - signed and game used equipment, seats from old torn down stadiums, advertising pieces, etc.