From research Here is the list:
Myanmar (also known as Burma)
Halong Bay, Vietnam
How to book?
You will be needed to do a little bit of digging and research to find a cheap flight. But most simple way is to check on comparison websites which will give u a lot of choices one you have decided follow the steps you will need a credit card, sometime the ticket will be on a word document meaning that you would have to print the document and shows it as a ticket when u get to the airport