I'm going to a conference next month at Yeditepe university and will most likely fly into Sabiha Gokcen airport. Any ideas on how much a taxi will cost between the two? Is there a cheaper way?

No specifics on taxi prices but there are bus options (albeit with a transfer).

Take the E-10 or 16S bus from the airport and get off at the 'Bostancı Sapağı' bus stop. Climb up the steps to the top of the Bostancı bridge and (without crossing the bridge) you will see a bus stop called 'Sanayii.' From there, the 14KS, 19, and 19C buses bring you right to the 'Yeditepe Üniv. Kampüs' bus stop.

You can check out iett.gov.tr for frequency and schedules.

I'm not sure about getting to Yeditepe from SAW but from the Bostanci bridge, it's about 11 YTL to campus via Taxi and should take about 15-20 mins barring a driver who doesn't know the way and/or major traffic delays.