I would have a discussion with my attorney & place the items in storage and notify their legal personal representative of their estate.

Instead, look at it as a chance to have a lot of one-on-one conversations.

As @Patricia Steiner said, in my state, an "As-Is" contract allows the buyer to walk away for any or no reason during the inspection period, while the "Standard" contract allows for the seller to remedy certain items to "working condition" and does not necessarily allow the buyer to back out scot-free.If you aren't sure of your contract, consult your Attorney, Realtor, or title company for some direction. 

There is an investment property that is over 3,000 sq ft filled with at one point high end items. 

I also have a direct and honest conversation with them over the phone before we show it that we are not done with the job and I point out all of the things we are still going to do to finish up. 

So you should have a conversation with the 2 or 3 of them to get a sense who you align with best.

When I sent the letter stating why i kept their entire deposit I would itemize everything to show that they owed a whole lot more than what I am keeping. 

Keep your meeting brief, in case they do not have the time for lengthy conversation at that moment.

It's a delicate conversation sometimes, but my subs are always appreciative when I can tell them, "all my bids were within 5%" versus "One bid was twice and much, and one was half as much."  

Yesterday I had an idea sparked by a recent podcast and a conversation with a BP member.