What the numbers say
Buy two, get one free: the customer pays $75.90 and takes three. Against selling two at full price, the free unit costs $12.16 per order: its unit cost, one more pick, and any change in the label for the extra weight.
Three for the price of two keeps $32.09 per order, against $44.25 for two at full price and $20.25 for one. The offer pays when it turns single-unit buyers into three-unit buyers; given to customers who were buying two, it only costs $12.16 an order.
Per visitor, it earns as much as selling one even if 36.9% fewer visitors buy.
Nature's Sunshine's Subscribe & Thrive takes 25% off every subscription order and ships it free. Nature's Sunshine, Subscribe & Thrive, read 23 September 2026
The cost structure, and where it comes from
| Price | $37.95, a bottle of supplements. Nature's Sunshine homepage, read 23 September 2026 |
|---|---|
| Unit cost | $10.47. From the reported gross margin: “Gross margin in 2025 increased to 72.4% compared to 71.5% in 2024.” Nature's Sunshine, fourth quarter and full year 2025 results, read 23 September 2026 |
| Pick and pack | $3.20 per order and $0.48 for each extra item. Fulfill.com, 3PL pricing benchmarks (The Fulfillment Advisor 2025 survey of 600+ warehouses), read 23 September 2026 |
| Shipping label | USPS Ground Advantage, commercial, Zone 5, by weight rounded up to the pound: 1 lb $9.29 · 2 lb $10.50 · 3 lb $12.12 · 4 lb $13.89 · 5 lb $14.53. Packed weight is an assumption: 0.5 lb per unit. USPS Notice 123, USPS Ground Advantage Commercial, Zone 5 (effective 4 October 2026), read 13 October 2026 |
| Card fees | 2.9% + $0.30 per order: Shopify Payments' online rate for a standard card on the Basic plan in the United States. Higher plans pay a lower rate, and premium cards a higher one. Shopify's pricing page for the United States, online standard card rates, read 12 October 2026 Rates by plan and country |
| Refund reserve | 5%, Offer Suite's default assumption for consumables. NRF's all-category figure for online sales is 19.3%, but consumables are rarely returned; use your own rate. |
| Gift | A travel-size bottle: unit cost $5.24, retail $15.00. A half-size bottle, costed at half the full bottle's unit cost. |
The offer, as an agent writes it
An agent writes this offer as one document for Offer Suite's API, validated against the offer schema. Below is one option of it: what the buyer gets and the price it promises. Offer Suite checks with a real cart that checkout charges exactly the prices above.
Show one option 2 options · excerpt
{
"key": "three-for-two",
"display": {
"title": "Buy 2, get 1 free"
},
"lines": [
{
"role": "main",
"quantity": 3,
"purchase": {
"type": "one_time"
}
}
],
"pricing": {
"promise": {
"firstChargeCents": 7590,
"renewalChargeCents": null
}
}
}How Offer Suite validates, versions and publishes a document like this one: offer documents.
Questions
Is buy 2, get 1 free profitable for supplement brands?
On these costs three units for the price of two keep $32.09 per order, more than the $20.25 one unit keeps and $12.16 less than two at full price.
What does the free unit cost supplement brands?
$12.16 per order here: a unit cost of $10.47, one more pick, and the heavier label where the third unit crosses a pound.