Just for comparison's sake GPTS is $150/credit hour, PRTS is $190/credit hour, RPTS is $255/credit hour, and my unholy alma mater PTS is $280/credit hour.
This gets us back to apples again.
Denominational schools receive funding from the denomination and the PCUSA is a very wealthy, old-money denomination. It is, as you suggest, a problematic school for those with confessional commitments or for those who hold the biblical view of Scripture. I suppose there are other ways in which getting an education at a mainline sem would be problematic.
Joel Beeke and Joey Pipa are friends and colleagues but those schools are not accredited in the usual sense of that word (e.g., regional accreditation or ATS). At the same time we are alike in that we are each confessional and conservative and seeking to serve the NAPARC churches.
Another factor to consider is size. Seminaries come in small, medium, and large.
GPTS, MARS, RTS/A, and PRTS are (for now) small schools. WSC was a still a small school (75 students) when I enrolled in 1984 but has since grown. There are advantages to attending a small school (e.g., student:teacher ratio) but smaller schools don't always have the facilities (e.g., library or support staff) that a larger school might have.
WSC is a middle-sized school (150 students; approx 120 FTE). We have limited our enrollment to 200. Our library has grown considerably since my student days! If one knows where to look in the library it's possible to see where the old wall was and how much it has expanded (and continues to expand in real books and in electronic journal/resource collection. Still, we have a very good student:teacher ratio.
WTS/P, Covenant, RTS (e.g., Orlando or Jackson or the considered as a system) are large schools (but not as large as Fuller or DTS).
There are a number of factors in comparing school. We might also consider location. Most Reformed seminaries are located in major metro areas or have migrated there. That affects cost of living but also presents different opportunities for ministry preparation. Some are in cold-weather locations and others in sun-belt locations (to where a good bit of the population shifted in the 1970s and 80s).
I'm also learning from the administration that schools calculate and report their costs differently. I don't work in the admin so I don't know the details but that's worth investigating.
I am appalled that any Christian, much less a future minister, would even consider just telling the school what they want to hear to save some money. Signing and agreeing to a confession that one does not truly hold to is lying and I would hope honoring the 9th commandment would be more important than getting a discount.
