He was known for taking trains as well, e.g. he was a frequent Amtrak rider: https://vault.si.com/vault/1980/11/17/clear-the-tracks-for-b...
The cars were usually built by a company like Pullman, usually from a time frame of roughly 1900 +/- 20 years.
Huge money pits, with tons of (often quite ornate) wood m, etc. then add the cost of restoration (again almost all of these cars are 100+ years old), retrofitting modern electrical systems, air conditioning. Could easily be a million dollar project.
But I mean, just look what a nice one is like inside.
Something like this one (Which I've actually been in)
The first time I realized this kind of thing was a tour of a baseball stadium. They showed us the suites. I forgot how much they cost but if you got a bunch of friends together to fill one then they were in the same range as medium good seats.
Example: https://www.mlb.com/padres/tickets/premium/suites Various prices, one is $4260 for 20 people. That's $213 each. Is that rich person's thing?
It wasn't clear what the private car costs but, just guessing the Train Jam did this. https://trainjam.com/faq You can see the prices for 52hr ride.