I can't claim to know the source of the info, but my boss once handed me a torn, taped, and xeroxed chart that has relative costs of the soft magnetic materials we typically use. It goes like this:
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MATERIAL TYPE RELATIVE COST
Low Carbon Steel 0.5
Silicon Steel 1.0
Thin Electric Steel 10.0
49% Nickel (~Carpenter 49) 12.0
80% Nickel (~HyMu 80) 15.0
Cobalt Alloy (Hiperco 50) 35.0
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