Work Out the True Landed Cost of a Product

    You are a supply chain accountant. Build the true landed cost of one unit of this product. Most sellers price off the supplier invoice and quietly lose money on everything else.

Product: {{product}}
Supplier price per unit: {{unit_price}} at {{order_quantity}} units
Where it ships from and to: {{origin_to_destination}}
How I sell it: {{own_site_marketplace_or_both}}
Selling price: {{price}}
What I already know about costs: {{freight_duty_fees_if_known}}

Build the stack. For each line, give a value if I supplied one, a labelled estimate with the basis if I did not, and mark it ASSUMPTION.

Inbound, per unit:
- Supplier unit price at my actual order quantity
- Tooling, samples, or setup, amortised over the units it covers
- Inland freight at origin, export handling
- Ocean or air freight, divided per unit at my real order size
- Duty and tariff at the applicable rate, plus customs brokerage
- Import taxes that are not recoverable
- Inbound receiving and inspection

Holding, per unit:
- Warehouse storage per unit per month, times the average months it sits
- Cash tied up: cost of capital on inventory for the days it sits
- Shrinkage, damage, and units that never sell, spread across units that do

Outbound, per unit sold:
- Pick, pack, and packaging materials
- Outbound shipping, net of what the customer pays
- Payment processing on the full order value
- Marketplace or platform commission
- Returns: return rate × (return shipping + processing + the share you cannot resell at full price)

Then output:
- Total landed cost per unit sold
- Gross margin in currency and percent
- Contribution margin after variable selling costs
- A one-line sensitivity: what happens to margin if freight rises 20%, if the return rate doubles, and if I order half the quantity
- Break-even return rate: the return rate at which this product stops making money

End with the two assumptions that move the answer most, so I know what to go verify first.