You can always negotiate

Once you have offer in hand.  Talk to PWC, tell that you have multifple offers.  You are most interested in theirs, becuase blah blah blah, however, you have other offers that are higher than them.  You wonder if they give a better offer.   Here they would ask you how much you want, it is your decision to just ask them to match or ask for 10,000, see what they would say...
personally I think it is a bad idea to ask if there is room to negotiate.  Just go ahead and negotiate.