Brian, sounds like a winner of a cabinet humidor for 5 bills. Now that you've mentioned the humidification system, it may just be a cabinet from the following company:
http://www.jcpendergast.com/Humidors.aspx
Don't hold me to it, but your "42" wide appears to be similar to some of the cabinets featured at the JC Pendergast web page.
I'm sure you'll know more once you arrive at the home where the cabinet is located for review. You may want to look for any labels that are affixed to the cabinet that would indicate the name of the company who built it.
Again, nice looking cabinet and good luck on the deal
