The online program starts August 2019. UPenn appears to be way ahead of the other Ivy League schools, except for maybe Columbia, in online education. https://www.sp2.upenn.edu/academics/ms-in-nonprofit-leadership/curriculum/
I couldn't find the tuition for the online program, and I don't think it's on the website yet. The tuition for the full-time program is for the on-campus option. The hybrid program is $58,830. The accelerated hybrid program is $35,436. My guess is that the online program will be cheaper than the on-campus, full-time program. https://www.sp2.upenn.edu/academics/ms-in-nonprofit-leadership/admissions-application/tuition-fees/