This may be more of an odd ball question.

When my agent reached out, the sellers said they have only gotten low ball offers and would consider accepting if they got an offer above the list price.

With today's market you pretty much can't low-ball anymore.

Something big with something of size in it,  like a stress ball or a payday.  

@Taylor Thompson Congrats on getting the ball rolling.

Without getting too personal, there are family and financial and factors here that make me think, if I had a crystal ball, I would not be surprised if she stayed here for four or five more years.

It looks like a "ring base station" is required to make these work, not sure if there is a work around, and also wondering if you'd need your own dedicated wifi in the house to connect all this too Owning a few properties myself and as a property manager for other investors I am imagining now the calls I would be getting when this system isn't working properly, batteries die, motorized lock stops working etc, so living in new england with the elements and temperatures we experience I would not recommend this to the owners of the properties I manage I have an up down style 2 family with a common entry door that sounds very similar to your setup.

Mostly what I'm saying is the best way for you to get an idea of what you are looking at is to have a builder walk the property with you and look over preliminary plans and give you a ball park of what you can expect. 

Somewhere in the ball park of 10%

@Sylvia B. - all original closet doors