Sounds like you really want this house. If that is the case, make sure to know your limit in terms of $$$, then do all appropriate inspections, and resolve to walk away from this property if need be.
Feel free to call me at 415-200-7202.
Also be sure you have really good inspections done, and check building department permit and inspection records to see if everything was done properly.
It does seem if she might be hiding something, that she might not want you to discover.