If you are on a budget, the most popular and convenient option, albeit not the most comfortable, is the tourist open-tour bus.  The open-tour buses cover most of the popular destinations between the North and South, and travelers can stop whenever they want for as long as they want in each destination along the way.  And at $26 USD for the entire journey between Hanoi and Ho Chi Minh City, and around $4-8 for individual legs, prices do not get much lower than this, although the bus operators make up for the low prices by herding you to buy and stay at the cafes, hotels and stops along the route. 

Tickets are easy to purchase at almost any budget travel agency at all of the destinations along the route, and tickets do not need to be purchased far in advance.  It is recommended, however, to reconfirm your seats one day in advance for the more popular legs, especially during the high season and holiday weekends.

Following are prices and travel time for some of the more popular routes:

Travel times and travel times are approximate and can vary according to company, as well as the number of stops along the way. For more information, including departure and arrival times, please contact the open tour bus operators: Toserco, Sinh Cafe, TNK Travel, TM Brothers, among others.

Public (Local) Bus

For those who prefer to travel more independently off the backpacker trail or have more of a local experience, there are public buses that run the same routes, as well as many additional routes throughout Vietnam.  Ticket prices are even lower, with tickets purchased directly at the bus stations in each city.