The five things that genuinely move a unit price
Quantity on the same specification. The most direct lever and the least interesting one. Setup is spread across more units, material is bought in larger quantities, packing is more efficient per unit, and machine time is better used. It only works if the artwork, the product and the garment specification stay the same; volume on a different design does not carry the setup saving across.
Fewer setups inside one order. Four products in one order share a production slot, a packing run and a delivery. Four separate orders do not. Consolidation is frequently worth more than increasing quantity on a single item, and buyers rarely check it because the four requests usually arrive from four departments on four deadlines.
Predictability. A programme known three months ahead lets a supplier buy fabric against a real requirement, schedule the run, and leave the setup ready for use. The same total volume arriving in three urgent batches produces three setups, three packing runs and three expedites, and the price difference shows up in exactly those lines.
Repeat orders with retained production assets. Where the same design is repeated on the same stock, previously prepared stencils, digitised embroidery files and mixed inks can often be reused. That removes an entire setup charge from the repeat. It has to be arranged: keep the artwork files organised, keep the specification stable, and tell the supplier the order is a repeat of a previous one rather than a new job with the same drawing.
Removing avoidable cost drivers. Simpler packing, fewer colours, consolidated delivery points, fewer approval rounds, a single artwork source instead of several, artwork delivered in a production-ready format, and accepting a standard lead time instead of an expedite. Each of these removes real work from the order, and none of them costs the buyer anything except planning.
Two things that do not move the unit price: the size of the company, and the length of the relationship on its own. A small company with a stable annual programme is easier to price well than a large one that sends forty different briefs. And a long relationship with no pattern and no forecast buys goodwill, not a better production cost.