I spent four months dealing online with BMW dealers for a steal. If they say no, they probably are serious. Usually they will play a few $100 here or there or start offering finance assistance if there is room to play the numbers, so "no" is probably just that.
As far as California, u will pay AZ tax and show proof of sales tax paid when u register in cali. U would only pay CA tax if u had bought in Oregon or in a no sales tax state.