Short answer. Usually not. The Civil Code treats business advertisements of things for sale as mere invitations to make an offer, not as definite offers. So the shopper is the one who makes the offer by agreeing to buy, and the seller is free to decline — unless the advertisement itself shows that a definite offer was intended.
What the law says
Unless it appears otherwise, business advertisements of things for sale are not definite offers, but mere invitations to make an offer.
Civil Code, Article 1325 — Business Advertisements. Read the full provision →
Who is offering, and who is accepting
A contract is perfected by the meeting of an offer and an absolute acceptance. The rule in this article decides which side is which. When a seller posts a price on a shelf, a website, a flyer or a social media page, the law treats that as an invitation addressed to the public — an announcement that he is open to receiving offers. It is the customer who makes the offer, by presenting the item at the counter or placing the order, and the seller who accepts or refuses. Until that acceptance, there is no contract, nothing to enforce, and no obligation to deliver at the posted price. That is why a store can pull an item or correct a price before it rings up the sale.
The exception: "unless it appears otherwise"
The rule is a default, not a ceiling, and the opening words matter. An advertisement can be worded so that it is a definite offer, and then it binds. What tends to make it definite is completeness and commitment: a specific identified item rather than a category, a stated price and quantity, a clear period of availability, and language promising to sell to whoever accepts on those terms — as distinct from the usual hedges such as "while stocks last", "subject to availability" or "prices may change without notice". Advertisements calling for bids stand on their own footing: the advertiser is not bound to accept the highest or lowest bidder unless the contrary appears.
What this rule does not excuse
Not being contractually bound is not the same as being free to mislead. Separate consumer legislation prohibits deceptive, unfair and unconscionable sales acts and false or misleading advertising, and is enforced administratively by the trade and industry authorities rather than through this Civil Code provision. A price posted with no intention of honouring it, used only to draw customers in and switch them to something dearer, is a different problem with different consequences, including administrative fines. A seller may also be bound once a genuine acceptance has occurred — an order confirmed and paid for is no longer a mere advertisement, and refusing to deliver at that stage is breach of an existing contract.
If a seller refuses to honour a posted price
Capture the evidence immediately, because listings are edited in seconds: screenshot the page with its date and price visible, photograph the shelf tag beside the item, and keep the flyer. Then work out how far the transaction went. If you only presented the item and were refused, you likely have no contract to enforce, though you may still have a consumer complaint. If you paid, received an order confirmation, or were issued a receipt, the seller's acceptance has probably already occurred and the analysis changes entirely. Send a written demand rather than arguing at the counter. If the amount is substantial or the seller stonewalls, book a consultation.