I think he's talked about working for a dollar a year anyways. Since he already owns the other places it'll be a heck uv a lot cheaper than it's been flying the first family around the world for vacation after vacation for eight years. Most presidents have had other places they like to hang out.
Oh, the Mooch's vacations, with entourage, are the stuff of any Marie Antoinette wannabe's dreams. They were excessive to the point of ridiculous, and had they been taken by a Republican First Lady, they would have been serious media fodder.
This isn't about what
she did. This is about the expense of having facilities in Trump Tower on par with those in the White House, security, communications (also secure), and being able to get the POTUS to secure command facilities in the event of sudden hostilities. Having him in New York City makes the town a strategic two-fer. Getting him out through air traffic in the event he needs to be relocated quickly is problematical. Most locations other Presidents went to were more easily secured, or already set up for the presence of the POTUS, or close to command facilities and had definable no-fly areas around them for security and exit purposes.
Just because estimates are less (I'm not sure what basis that is done on since the nature of those facilities isn't really common knowledge--construction specs, equipment, comms, etc.) setting up new ones elsewhere might prove even more expensive than the Mooch's sojourns.
I seriously doubt $399,999.00 (if he works for a dollar a year) will cover that expense.