Two magnesium oxysulfate cleanroom panels can carry the same A1 label on the RFQ and still land 40–120% apart at the dock. The gap is not margin alone — it sits in MgO/MgSO₄ activity and chloride residue, glass-fiber mesh grade and ply count, core density and curing cycle, face skin (pre-painted steel / PVDF color steel / 304-316L stainless), adhesive system and continuous-line versus hand-laid lamination. This module decodes the cost stack for overseas procurement engineers, fire-protection subcontractors and pharma/food GMP buyers so a magnesium oxysulfate cleanroom panels bid can be priced on verified formulation, not on catalog photos. SAMZOON, a Foshan source manufacturer, anchors the walkthrough with controlled low-halogen cores, four-side sealed profiles, free pre-bid samples and South China purification project QC.