Cheap MS bar or cage, MIG welded is cheap. That's because welded tube is cheap DOM mild steel is almost as expensive as moly. I can definitely see how a 4130 Moly Bar that must be TIG welded can be 3 times the price. But its lighter, stronger and TIG welds look a lot nicer.

FWIW Mine is Moly. Do it once, and do it right.