The expensive mistake in supplier data is not the scrape failing — it is the scrape
succeeding and you reading the wrong column. Three checks before any margin enters a spreadsheet.
1. Retail or cost?
A distributor catalogue shows the consumer price on the storefront and the cost only
inside the reseller area, behind a login. Scrape the storefront and call it cost, and your “margin”
is fiction — the product looks like 60% when it is 5%.
Confirm the side of the table before calculating: the same page often shows both, with different
labels.
2. Shipping picks the SKU, not the percentage
With shipping baked in, a cheap item does not survive: a R$ 16 product with R$ 22.90 shipping
gives no margin — it gives a loss, however good the percentage looks. The SKU that pays the bills
is the high-ticket one.
real margin = sale price - item cost - shipping - payment fee
Before choosing a catalogue, ask for the shipping label cost. That is the number that changes the
product list, not the commission.
3. The number that matters is the month, not the item
Add the platform subscription to the fixed cost: if the plan costs R$ 99.90/month and the margin
per item is R$ 55, the plan pays for itself in 2 sales. With 20 sales in the month, profit is the
sum of margins minus the subscription — not the margin of a single sale.
How to scrape it properly
Look for the number on more than one pageStorefront, product page and reseller area
usually disagree. The disagreement is the information.Verify the response bodyA 200 does not guarantee you received the price page
(blocks and consent screens return 200 too).Record the measurement dateSupplier prices move; a margin with no date is not
auditable.
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