A marketplace product page usually carries a single visible price, but several sellers may be offering the same item behind it. Which one you see is decided by an algorithm.
One listing, many sellers
Marketplaces group identical products onto a single page rather than creating a separate listing for each seller, which keeps search results usable.
The default seller occupies the position that the buy button acts on, and the overwhelming majority of orders go to whoever holds it.
Other offers remain available through a secondary list, but few shoppers open it, so the default position is effectively the whole market. Sellers compete for that single slot rather than for the shopper's attention, which is a very different contest from a shelf of rival products.
Selection weighs more than price
The algorithm considers delivery speed, fulfilment method, order defect rates, cancellation history and customer service performance alongside the price itself.
A seller charging slightly more with faster shipping and a stronger record can hold the position against a cheaper competitor.
This is why the visible price is sometimes not the lowest available, and why checking the other offers occasionally reveals a meaningful saving.
Fulfilment method carries heavy weight
Sellers who store stock in the marketplace's own warehouses inherit its delivery speed and returns handling, which improves their standing considerably.
Sellers shipping themselves must demonstrate comparable performance to compete, and any slip in dispatch times affects their eligibility.
The cost of using the marketplace's fulfilment is therefore partly a cost of visibility rather than purely a logistics charge.
The position rotates continuously
Eligibility is recalculated constantly, so the default seller can change through the day as stock levels, prices and performance metrics move.
Sometimes no seller qualifies and the buy button is replaced by a list of offers, which usually signals a pricing dispute or a stock problem.
These rotations explain why a price seen yesterday cannot always be reproduced today even though the listing appears unchanged.
Reading a listing more carefully
Checking who is selling and who is dispatching an item takes a moment and distinguishes the marketplace operator from a third party using the same page.
The other offers list shows the true spread, including sellers with lower prices and slower delivery that suit a buyer in no hurry.
Returns handling and warranty support can differ between sellers on one listing, which matters more than the price gap on higher-value goods. A small saving is poor compensation for a refund that has to be arranged through an unfamiliar third party rather than the marketplace itself.