What is anyone's experience with cost comparisons between a conventional steel framed structure versus metal building framing.  Not pre-engineered metal building, but a custom building using metal building components.  Conventional steel framed building is hot-rolled wide-flanged beams and columns, bar joist and metal deck roof, cold-formed stud walls.  Custom metal building is one that does not utilize the metal wall and roof panels, but a different veneer system such as brick and a standing-seam roof with rigid insulation.  I work with several architects who believe that as long as the structural framing is metal building components, the building costs must be significanly less.  I contend that as long as the owner uses an off-the-shelf pre-engineered metal building with no modifications, that is the most economical.  When either system is custom designed, there really is not a signifant difference in cost between a custom metal building and a conventional steel framed structure.  Assuming the foundation is essentially the same regardless of framing system.  I know there are alot of variables involved, but wondering if in general terms, am I off base here?  Looking at the RS Means data, I believe I am correct.