When making an offer be realistic about your offer, if an item is a Buy Now item of say £100 but has the option to make an offer for the item, then the chances are the seller is not going to accept your offer of £10 or even £50, the likely hood is that the seller would like to get as near to the buy now price as possible, as a guide I would say to offer about 75% of the asking price, if that offer is declined then after 48 hours have elapsed and/or the offer is declined, then try 80% then 85% and so on, however, the danger in this concept is that someone may make a more realistic offer just after you and the offer could be accepted for them, that is all well and good if you was really unwilling to pay the winning offer amount for it, but can be really disappointing if you wanted the item.
The reason why we list most of our items as Buy Now plus Make an Offer is due to providing the customer with what they want or need in a very short space of time, they don’t have to wait days on end to see if they will win the item, or if someone who really wants the item is going to push up the price or snipe it at the last minute.
Over all I believe that Making and Offer is one of the best things ebay has introduced, it gives the buyer and the seller freedom to both achieve their objectives. The seller is pleased because the item sold at an amount that they accept, and the buyer wins the item for the price they are willing to pay.
To finish up, keep in mind that making an offer is a binding contract, the same as bidding or clicking Buy Now. Please read ebayer terms for more information on this topic. http://pages.ebay.co.uk/help/sell/best-offer.html