Deciding Whether to Buy Neighbor's House

[Suzy R.]

Hi BP Community,

I have a wonderful and kind neighbor who has used her house as a storage unit for about 20 years. She stores stuff there, but lives elsewhere.  She purchased the house for $299k in 1999.  In 2017 it was appraised at $247k. Zillow estimate is $357k.  It is 3 bed/1.5 bath on 1.45 acre just outside city limits.  The house was built in 1966.  In 1999 when she bought it, it was beautifully maintained.  Now it is in very poor condition with a large amount of deferred maintenance.  The land is overgrown and unmaintained.  She recently let me know she is considering selling it and would love for it to go to us. I have had a long time dream of turning this house into a beautiful furnished rental or B&B or airbnb.  I think it could be a profitable flip, but I want to keep the property. I am struggling with the following:

How to properly value this property considering the condition it is in...

How to value an awkward and somewhat unusable acre...it is shaped like a large splinter.

Wanting to maintain friendship with my neighbor and respect her and her property while still trying to get the property at a price that makes it a wise investment...

Emotionally, I really want this property because of what I would love to do with it.  Numbers-wise,  it would be very hard for this to make sense as a good investment.  

Does anyone have any experience with or advice for this sort of situation?