I believe a listed price is an "invitation to treat" which means a retailer can charge whatever they like regardless of listed price (whether in a physical or online store), but at what point can't an online retailer cancel/back-out of a transaction? Let's say the merchant and buyer are both California-based for simplicity. Would it be legally similar to "theft by discovery" (e.g., taking money falling out from an overturned armored truck) for accepting goods sold at an excessive, erroneous discount? Or would it require proving intent on part of the buyer that the price was a serious mistake they deliberately acted in bad-faith to exploit?
Let's say the (over-simplified) phases of a transaction are:
1. Agreed - Buyer clicks "Buy".
2. Paid - Payment is posted.
3. Shipped out - The product leaves the custody of the merchant.
4. Received - Customer receives the product.