When should a buyer's order be finalized for it to be legally binding?

A buyer's order becomes legally binding when a price agreement has been reached and both parties have provided their signatures. This is a crucial step in the sales process as it indicates that both the buyer and the seller acknowledge and agree to the terms of the sale, including the agreed-upon price for the vehicle.

Finalizing the buyer's order at this stage ensures that all parties are clear on the details of the transaction, which helps prevent any misunderstandings or disputes later on. Once the signatures are in place, the order is legally enforceable, meaning that either party could be held accountable for adhering to the terms outlined in that document.

In contrast, the other scenarios mentioned do not mark the formal finalization of the sale. Delivering the vehicle or waiting for financing approval occurs after the buyer's order has already been placed and finalized. Payment of the vehicle also happens after an agreement has been established; it does not constitute the moment the deal becomes binding. Therefore, the correct answer emphasizes the importance of the agreement and signatures as the foundational elements that make the buyer's order legally binding.