That way when you sell the car you can put the stock CD player back in. Keep the aftermarket one for your next car, or sell it to some kid in high school for too much money to put towards a new one.
thats low compaired to a few years ago, they where all hitting at least $100 on ebay ... I know i got a factory cd player for about $70 and turned around ans sold it a few weeks later for about $100 a few years back ...