One alternative would have been to do a 2nd layer of asphalt shingles. This would have been inexpensive, but a questionable direction if a photo-voltaic array were pursued in the future for the building. Also, because we had waited, the 1st layer had started to curl in addition to the numerous patches we had to undertake.
We also choose a special reflective pigment to increase the reflectivity of the surface (emmisivity of radiation) and reduce the absorption of heat by the building. Such a roof will have a 40+yr life.
A coil of material is formed on site with special equipment that "rolls" the flat sheet into a profile, and with a CNC controlled hydraulic "flying" sheer, can cut the material as it continuously comes out the end. Think of it as "Playdough" in one end, and in a profile after coming through the form (although it isn't really an extruded process like playdough).
We were very satisfied with the Contractor, Tell them that IDA in Derby referred you:
Standing Seam Roofing Company LLC
West Haven, CT. 06516