I have been negotiating a deal with a supplier for my company. Boss said she was happy with the deal at a high level and asked me to speak with the supplier to ensure that they do not increase the prices as our requirements were bespoke. I managed to negotiate a 5% reduction in price while we got the bespoke product. Now the Boss wants me to re-negotiate with the supplier to less than half the price which has been agreed to:-(. Needless to say, I do not know what arguments do I put in front of the supplier to be able to negotiate further like this. My boss is quite difficult to work with. She is not a detailed person. I do not want to go back to her and ask her how do I negotiate to less than half the price like this. Appreciate inputs here.