If your customer has sent you a message about a fixed price listing, you can send them a Private Offer to suggest a discounted price.
Once you've sent the offer, the buyer will receive an email with the details. The offer will automatically expire after 48 hours. If the buyer accepts the offer and completes the purchase, you will get an update via email.
Note: You can send an offer to multiple buyers. However, you can send only one offer at a time to the same buyer. If you want to send a revised offer to the same buyer, you need to cancel the original offer first.