buying off market seller wants appraisal first

[Chris Ryan]

I am looking for tips on how to negotiate a property from a seller that will be getting an appraisal in a few months when she is back up for the summer as this is their summer home.  I would like to try to lock this up prior to her getting the appraisal and listing it. We could split the agents fees off the price of the house.  I want to avoid the competition from non investors as this it a desirable area.  This will be a buy and hold and use as a vacation home when its not rented.

If she wants to wait and get the appraisal, do I trust it? Or get my own if I don't like it? She is 90+.   She did reach out to me as I expressed interest a year ago to her.  She is my families neighbor.  

I have a friend that is a realtor running a report on recent comps and and will give me a number that he would list it for.

Thank you all!