Probably more than you want to know ...from Chat GPT...
In most cases, advertisements (including classified ads) are not legally binding offers. Instead, they are invitations to negotiate or invite others to make an offer.
The seller is not legally obligated to sell the item to anyone who responds to the ad; instead, a buyer makes an offer to buy the item and the seller can accept or reject it.
Why Classified Ads Are Not Unilateral Offers
• A unilateral offer requires clear intent to be bound once the requested act is performed (e.g., returning a lost item for a reward).
A classified ad usually lacks this intent. It does not promise the item to the first responder but invites interested parties to negotiate the terms. Terms can include timing, method of payment, who pays shipping, etc.
A contract for the sale of the item is only formed when
1. A buyer makes an offer (e.g., "I'll pay $200 for the item").
2. The seller accepts the offer (e.g., "Deal, it's yours for $200").
Until then, either party can walk away without legal liability.