Dear Robert,

Thanks for your message left to us.

At first, I would like to let your know that it is possible to buy the China train tickets from us in U.S. dollars, but it is a bit complicated and need to pay more.
 

More information about foreigners buying train tickets in China offered as below,

1. Foreign visitors can buy train tickets by their passports or residence permits for foreigners. Using passport is easier.
2. 1)Foreign visitors can buy train tickets(paper ticket) at the counter in ticketing hall of station by the passport or passport copy.  

           2)Reserve at the site: https://www.12306.cn/en/index.html , then show your passport at the counter in ticketing hall of station before check in the train, to get the paper ticket.

 For this way, you will need to register firstly, then buy it online. As it is new and only for foreigners with passport, therefore, I am not sure whether passengers can pay by foreign credit card or not. This way is easier and it is what I suggest you to try first.

3. When you check in at the station, you will need to show your passport or other identification which you used for ticket booking. Just like check in air plane.
    

If you need to book from us travel agency, more information as below for reference,

1. Now the tickets can be booked and issued 15 days before traveling date.
2. As we are based in Guilin, a city in southern China, we can only buy the paper tickets from our city. Then we will need to deliver the paper tickets to your hotel or any certain who can receive the tickets and give it to you in the starting city. In this case, if you book through us travel agency, it will cause our service fee and delivery fee(handling fee:US$8 per ticket in total).
3. For the booking, we will need your traveling date, from where to where, how many passengers, passengers passport copies, where or who we can deliver to as well as the contact person’s number

Further updated information for China Entry

Starting from 15 March 2021, the Ministry of Foreign Affairs of China will provide the following facilitation for visa applicants who have been inoculated with COVID-19 vaccines produced in China and obtained the vaccination certificate:
 

(1) Foreign nationals and their family members visiting the mainland of China for resuming work and production in various fields need only to provide the documents required before the COVID-19 pandemic when applying for a visa.

(2) The scope of applicants eligible for applying for a visa out of emergency humanitarian needs will be expanded as appropriate. Foreign family members of Chinese citizens or permanent residents of China, including spouse, parents, children and other close relatives living together (referring to siblings, grandparents and grandchildren), may submit visa applications for the purposes of reuniting with family, taking care of the elderly, visiting relatives, attending funerals or visiting critically ill relatives.

(3) Holders of valid APEC business travel cards may apply for the M visa by presenting the original valid APEC business travel card and the invitation letter issued by the inviting party in the mainland of China.
 

Reminder:

(1) The above-mentioned visa facilitation applies only to applicants who have been inoculated with COVID-19 vaccines produced in China (either having received two doses of Chinese-made vaccines with the stipulated gap in between, or having received a single-dose Chinese-made vaccine at least 14 days prior to the application) and obtained the vaccination certificate.

(2) All passengers should still follow the boarding requirements as stated in the Notice on Airline Boarding Requirements for Certificates of Negative Nucleic Acid and Anti-Body Blood Tests Results.

(3) After entering China, you are requested to comply with the relevant epidemic prevention regulations. For detailed procedures, please check the official websites of Chinese embassies in various countries.
 

As of March 18, the following China embassies have issued specific notices:

Hong Kong, Macau, Japan, Thailand, Vietnam, Cambodia, Pakistan, Sri Lanka, Israel, Philippines, Malta, Belarus, Ireland, Belgium, Norway, Finland, Greece, India, Spain, Serbia, United Kingdom, South Korea, Denmark, Australia,Slovakia, Micronesia, East Timor, Indonesia, Arabia, Giles, Germany, Switzerland, Romania, United States, Turkey, Nepal, Jordan, Italy, Argentina, Estonia, Bulgaria, Croatia, Latvia, Luxembourg, Malta, Gabon, Nigeria, Rwanda, Ivory Coast.