Contribution per sale = realised price − landed product cost − payment fee − variable allowance − any additional variable expense. Here: $2.50 − $0.90 − $0.10 − $0.15 = $1.35. The allowance is a simplified planning input for losses, customer cases and other attributable variable costs.
Monthly operating contribution = retained sales × $1.35 − $540. At 300 sales: $405 − $540 = −$135. At 700: $945 − $540 = $405. At 1,200: $1,620 − $540 = $1,080.
Simple cash recovery = initial launch cash ÷ positive monthly operating contribution. The working case is $8,100 ÷ $405 = 20.0 months. The busier case is $8,100 ÷ $1,080 = 7.5 months. A non-positive contribution gives no finite recovery under unchanged assumptions.
Operating break-even is $540 ÷ $1.35 = 400 sales per month. A 24-month recovery target is ($540 + $8,100 ÷ 24) ÷ $1.35 = 650 retained sales per month.
Include venue rent or commission, refill labour, travel, utilities, software, connectivity, insurance and maintenance. Treat sales-dependent expenses as variable, revise unit contribution accordingly and count every expense once. Initial cash includes opening inventory funding; the monthly product cost represents replacement stock.
The examples exclude financing, tax, depreciation, ramp-up, discounting, residual value and changing working capital. They assume stable contribution and fixed costs. Simple recovery is a planning measure, not accounting ROI or a promised return.
