For four days in mid-July, researchers at Procon Campinas, the consumer protection agency in the Brazilian city, clicked through the websites of five online retailers, logging prices for 62 items. Their ledger, released ahead of Father’s Day on 9 August, turned up a striking arithmetic: a futsal ball that could cost one shopper 173.3% more than another, depending on the store. The survey, conducted from 13 to 16 July, covered seven categories from clothing to tools, and kept only items found in at least three establishments.

The largest discrepancies clustered around the kind of gifts a son or daughter might buy on a Sunday. A wireless induction charger varied by 167.9%, a gamer headset by 153.9%. Even the bookshelves were not immune: “Rich Dad Poor Dad” (Pai Rico, Pai Pobre) ranged by 120.5%, while “How to Win Friends and Influence People” (Como Fazer Amigos & Influenciar Pessoas) varied by exactly 100%. At the other extreme, some products barely moved—the book “The Power of Habit” differed by just 1% across stores, and a drill by 8.9%.

The survey’s director, Paulo Giglio, used the data to urge restraint. “The consumer should not buy on impulse,” he said. “Researching prices in different establishments is the best way to find good opportunities and avoid paying more for the same product.” He added that shoppers should weigh their own budgets and avoid debt. The findings were intended as an educational tool, not for advertising, and reflected only the prices captured during the four-day window.

The broader mood among Brazilian shoppers appears to match that advice. In Sorocaba, a separate survey commissioned by the local commercial association found that 64% of consumers planned to buy Father’s Day gifts. That poll, which heard 192 people, pointed to a more deliberate approach: shoppers were buying earlier, seeking better value, and splitting between gifts under R$100 and those above R$250. Clothing, perfume, footwear and accessories led the list, with electronics showing potential growth. Credit cards remained the main payment method, though the Pix instant-transfer system was gaining ground.

What lingers is the image of the patient shopper, a list of prices in hand, standing before a shelf where a futsal ball might cost double its neighbour. The contrast between the 173% swing for that ball and the 1% variation for a popular book is a quiet reminder that in the Brazilian retail market, the same object can carry very different prices depending on where—and when—you look.