Call a local metal roofing supplier and explain you are planning on replacing your roof yourself. Ask for price per square (100 sq. f.t) or per ft. of panel of various types of metal roofing. Standing seam, delta-rib, corrugated, etc. Have your sq. ft. of roofing area, pitch and other details available so you can sound like you mean business.
On top of materials, you will need to factor in tear-off of your existing ($$) as well as labor for installation of the new roof. Beyond pure labor is skill and experience, technique, attention to detail etc. that results in a good metal roofing job. This is why in my design-build practice we install our own metal roofing.