In other states, sellers sometimes actually pay the closing costs as a negotiated deal.
Would they do that in NY? How motivated are they to sell...it is like negotiating the price down. And yes, you really should have a Realtor negotiating this for you.
You might as well ask the seller now instead of just a few days before instead of waiting.
Yes you should have an agent help you in this process because more than likely, they have done it before.