Thanks everyone.

gogate99 - unfortunately I will use the second airport, Sabiha Gokcen (SWA) which is less convenient but has more "budget" flights. According to Pegasus' site, they suggest passengers to show up 2 hrs. before dept. Do you happen to know how strict are they with this? My flight is at 8:00A something so that means waking up really early to catch the bus from Taksim to the airport.