(by Mathias Elrød Madsen)
For a more detailed guide to negotiation, please read the book “Never Split the Difference: Negotiating as if your life depended on it”
Obviously the method is not bullet proof and my experience has been that sometimes you get an even better price than you went for and sometimes you cannot get them to go as low as you aimed for.
Rather than playing the role of a tough negotiator, be friendly and understanding. Act like you and the salesperson are in the same boat in the sense that you are both interested in finding a price that both parties can live with. More than negotiating you are actually cooperating on reaching this shared goal.
One specific way of doing this is for instance to make your superior the one who says no instead of you.
Here is an example of what a response to an offer that is still not good enough could be:
"Thank you for your last offer, I really appreciate you trying to accommodate me. Unfortunately, X is still more than my boss is willing to pay (or: However, I just talked to my boss and unfortunately x is still more than we can afford to spend on an ad like this). I realise you also need to make your boss happy, but what do you think of Y?"
There are of course cultural differences when it comes to negotiating, however hopefully you can use the above to some extent.