hi, who would actually do the closing for my friend, she wants to sell her liquor store..sale by owner?

Your friend is selling commercial real estate.  She may at the very least want to have an attorney look over the contract and closing documents, this would not likely cost more than a few hundred dollars but could keep her off the hook for thousands of dollars worth of liability. To answer your question I've never seen a "due diligence checklist" because each transaction is unique.  Also, it is likely that a title agency will perform the actual closing.   I can help, Don Eby 303-688-0944