As i already said "There isn't any market for negotiations. Only other people (in the same server) can make offers for your players."
If you can see the option make an offer that means you are in the same server, therefore you can proceed with the offer.

If you are looking for any player or want to sell players via negotiation you can post in this thread: http://forum.topeleven.com/top-eleve...er-market.html