But in this case, you've already sequestered yourself into a one year commitment, and the other person has conceded nothing. If I know you're available to commit, I just need to find your discount level. You're going to underestimate my acquisition costs, I can guarantee that.

Better to suggest: "I really like your product here, but to be frank, I've got to watch my money right now. Is there a way you can reduce this price 20% and still do business with me?"

The catch is that some people will most certainly say no. You either deal with them and reward their stubbornness or walk to someone that is willing to talk. I think that's more of the key than an opening line.