One of the things I always have a hard time adjusting is the budget. Last month I made two trips, in one I spent only 20 USD, but in the other we all spent more than 100 USD, well we were 5 people. I think it was proportional, but we still paid the bill between three people.
My brother went through Bolivia and told me that it is extremely economical. Mainly because of the exchange rate, but the most interesting thing is how you can change those prices in an adjusted way. You always have to look for it, walk, of course, while protecting your safety.
One of the things that has always helped me is not to eat salads or sauces when I am traveling because they can go bad. This also helps when it comes to lowering the food budget (you know you should opt for cooked food). :P