DU is not catholic, but was founded by Methodists. It has a school of theology, but it is separate from the undergrad school. Not physically separate, but separate administration.
Tuition for OOS in Boulder is not $50k, but COA certainly can be. COA for instate can be close to $30k depending on the housing, major, transportation or car expenses. There are also CU campuses in downtown Denver, in Colo Springs, and the medical campus in Denver/Aurora (medical, dental, nursing, and related majors).