Q: Why do zipper prices change with order quantity?
Unit price falls with quantity because fixed costs are spread over more pieces. The fixed part includes machine setup, tape dyeing minimum, plating barrel load, tooling amortisation and quality inspection. The variable part is material and labour. As a result, the price curve is steep at small quantities and flattens at large ones. Suppliers usually publish two or three tiers rather than a formula. Ask where the tier boundaries sit and why, then check whether your annual volume could be ordered in fewer, larger releases to reach a better band. Holding stock can help, but it ties up cash and risks obsolescence if the style changes. A second lever is standardisation: one tape colour and one slider across several styles reduces setup. Be careful with a very low quote for a small quantity; it may exclude a process, use a lower grade of tape, or assume a tolerance you have not agreed. Compare quotations at the same specification and the same tier.