As long as you are asking about real estate, everything can be negotiated. You can negotiate price, terms, dates interest rates, taxes--but do it BEFORE you sign anything having to do with the contract. As they say, marry in haste, repent at leisure.
We agree that everything is negotiable but feel you would be best served by the support of a real estate professional. Negotiated offers are best when based on factual information that agents have access to and know how to use.