Quality control is mostly decided before anything ships, by whether your specification is measurable. Write the spec in attributes that can be tested — moisture percentage, grade, defect tolerance, dimensions, purity, packaging type — rather than adjectives like premium or export quality, which cannot be arbitrated. Then layer three controls in order of cost. A sample screens whether the supplier can produce the thing at all, and only helps if you retain a sealed, dated portion as the reference the bulk order must match. Pre-shipment inspection is the real control on a bulk order: SGS, Bureau Veritas, Intertek and Cotecna each run these for roughly USD 150 to 300 over two to five days, checking quantity, specification conformity and packing before the goods leave. A full factory audit covering capacity, quality systems and ownership starts around USD 1,000 and takes one to three weeks, and is proportionate on a large or repeating programme. Commission every report yourself rather than accepting one the supplier arranged, because a report the counterparty controlled is not independent evidence. Finally, tie the payment structure to the control: funds released only on confirmed delivery, with inspection as part of the release condition, is what converts a quality standard into leverage instead of a hope.