If you are traveling overland, the only way to get a Bolivian visa is at the border. Yes, British, Australians and many other nationalities do not require Bolivian visas to enter Bolivia, but we did. We waited for over half an hour standing at one of the Bolivian immigration office windows at the border to get the visa.
Here is what you need to get your visa:
1. Valid passport (at least 6 months)
2. One recent photo
3. US$135 per person (cash)
4. Filled out a special form for American visitors
5. Pen to fill out the form
Sometimes they may require a yellow fever shot certificate. We were advised by the Bolivian consulate in Montevideo to have yellow fever vaccination.