You can do a simple google search and find out the cost of attendance at other more expensive schools, but not everyone is applying to those schools. Last I remember, this is a UPenn thread and the fact that there are more expensive schools doesn't make UPenn any cheaper. It's still considered quite expensive.
Besides, if you didn't get the gist of it, I was only joking anyway. You probably don't want to ask this at your interview or about the cheesesteaks. Point is the applicant/interviewer should make a list of questions based on what he/she wants to get out of school. The school's website is a good place to start.