http://career-advice.monster.com/salary-benefits/negotiation-tips/the-right-words-how-to-ask-for-more-money-hot-jobs/article.aspx
http://www.careerhelp.umn.edu/PDFs/Salary%20Negotiation.pdf

5. “Do you have any flexibility in that number?”

Once the interviewer has named his or her offer, use this phrase for a smooth transition into a negotiation.

6. “I’m a bit disappointed with your offer, can we discuss this further?”

If you wish to negotiate on the initial offer, this is another great phrase to start the conversation.

7. “That sounds like a good starting place, can we negotiate on the details?”

Another tactful phrase to respectfully ask for a higher salary.

8. “Can we get that in writing?”