How much is a self-help tour to Vietnam (about 3 days)

If it is only a few days, the money spent on passports and visas is not worthwhile. I suggest you go to the border to entrust a travel agency and find a regular one. You can save a lot of money. If you really want to travel by yourself, you should first apply for a passport (the account takes about 14 working days, and the cost is 200), get a good passport, and apply for a tourist visa at the Vietnamese Consulate in Nanning, China (the cost is about 400, and it takes 3-5 days), and then you can cross the border to Vietnam to start a self-help tour. Time is limited. I recommend you to visit Hanoi, Haiphong and Halong Bay. Can't go to the south and west (there is not enough time).