Model built from 731 days of reconstructed fulfillment history. In-house option assumes 12,000 sq ft @ $1.15/sq ft/mo (3-yr lease), $14k fit-out, $85k equipment (7-yr depr.), 6 FTE baseline + 1 FTE per 8k orders above 25k/mo, $1,400/mo WMS, $0.78/lb outbound shipping, 60% efficiency in months 1–3. All costs discounted at the selected cost of capital.