Tell them that you got a friend whom bought with that spec and price.
If they are not happy with it, be prepare to walk out.
I did and he called me back the next working day for further negotiation. I did not budge with my offer. He called me back again and agreed with the price. I am sure that price could go further down by a few hundreds but it is going to be too difficult and no point wasting more time.
Thanks man, but I think this is the way useful in the bigger city, not in the ACT!! I walked out from two dealers here, non of them called me again!!!!