Negotiating is exactly that...negotiating. But it is also calling one person's bluff.
It either is the final offer or it is not. But, read on...it does not have to be the final offer, even if you accept the offer.
The beauty of Sedo's new and revised system is this...if you can live with the offer, accept the offer BUT TAKE IT TO AUCTION!
This will maximize revenue with the Sedo audience plus give it added exposure that it would most likely not get. The only way to successfully get a domain to auction is to accept an offer and then indicate in the control panel that you want to take the domain name to auction. The other method is to work with a broker. This is a farce. Even with my connections at Sedo, all they are interested in doing is brokering (selling) my entire domain portfolio.
The new auction format is quite popular and has been quite successful for domain sellers. TRACTORS.COM sold on this format for $143,500.00. Doubtful that the seller would have negotiated such a high price. In reality, his/her reserve was about 1/5 that amount so, no...he would never had gotten that kind of jack had he not taken it to auction.
It was the Sedo crowd who saw the domain featured in the auctions and went crazy over it. I am equally sure that the word quickly got out on other sites of the domain's popularity and drew more folks into Sedo's fold.
So, if you are happy with the offer and can live with it, take it to auction. The least you will get is the offer (you MUST sell it for this amount if there are no more bidders) or other users will go ga-ga over it and run it up.
I hope what ever you are selling brings you $143K.