What is the cheapest way to travel to Panama Central America by bus or train from San Antonio Texas?

I would like to travel to Panama sometime this year. I was wondering how much it would be to travel from San Antonio, Texas to Panama Central America by bus or train? Has anyone ever made this trip? I googled it but cannot find an answer. Any websites? Tips and info? Thanks!

Make it by plane.
It should'nt be much more expensive than by bus.
In the USA I don't know, but in Mexico and Central America, they don't have so developed railroad network for passengers, and by bus, it could be expensive and very boring and tired.

There are no trains. I love trains, but not happening.
Bus or plane.

You can take a bus from San Antonio to Mexico City and then from there to Tapachula, the border on the Pacific side.

Last August, I took the bus from Panama City to Tapachula, the border of Mexico. I had every intent to continue on to Mexico City but my traveling companion became very ill. The rest of the trip was canceled.

The buses are not bad. They are comfortable and air conditioned.

They have rest rooms.

They stop for meals and sometimes stop to let a vendor on who will go from row to row and sell sandwiches and drinks, then get off.

From the Mexican Border you can take the Tica Bus, a Costa Rican company, all the way to the bus terminal in Panama City. Tica Bus has a website with prices and schedules out of each city. Tica Bus has two classes of service. The higher priced one is the "Executive" class. You get a bigger more
comfortable seat and a more upscale clientèle riding with you. The price is a bit higher.

The ride is good. You get to see the country side (something you can't do from that aluminum tube at 30,000 feet) and get to know the people.

I am reluctant to tell you how much it was, because it was almost a year ago and everything has gone up since then. But it was half the price we would have paid if we flew.

You will need some dollars at each international crossing. Each country will extract ten to twenty bucks depending on the country for the privilege of riding through it.

Check for the Tica Bus website: ticabus.com and at the top, on the right, click English.

You'll have a mini adventure on the bus. On the plane you'll get there faster, lighter in the wallet but pretty boring.