Crossed the border by bus, from Peru. The old-fashioned way. Since I was the only American and the bus driver wanted to keep the group moving to La Paz, I was singled out and told to follow a border guard to a dark, dingy office where behind the dark, dingy desk, sat a young, cocky border agent whose job it was to take my $135 bucks and give me a visa. Make sure you carry a copy of your passport on you. You need that to get the visa. Otherwise, it's a pretty simple process. Cash only.