When to use Best Offer
You should use Best Offer only when you?re serious about purchasing the item, service or property at your Best Offer price. Like the bids made on auction-style listings, your Best Offer is binding. if your offer is accepted by the seller, you are obligated to pay for the item, service or property.
Best Offers are good for 48 hours. If the seller accepts your offer, the listing is immediately closed.
Best Offer gives you the chance to negotiate the price with the seller. One advantage of a Best Offer is that you have the opportunity to buy the item at a lower price than the Buy It Now price. There is no minimum Best Offer price. However, you should only make what you consider to be your "best" offer for the item because any seller who receives multiple offers for an item is likely to accept the highest Best Offer.
Tip: To get an idea of a typical selling price for the item you are considering, you can search for completed listings.