First of all, if you are crossing into Brazil from Argentina at Iguazu Falls, half the time they don't even look for your visa (especially if you are crossing in a taxi and the driver says you're only going for the day). When we crossed there, we literally had to argue with the Brazilian official to stamp our visa (you have to validate it by entering the country within 90 days of the date it is put into your passport or it is no longer considered valid, and we were warned by the Brazilian consulate that at Iguazu we might have to "remind them" to validate it). But if they do check, you're stuck. And you didn't say where you were entering. So I would suck it up and buy the visa. Once you validate it, it's good for 5 years (at least it used to be). I promise that you will want to go back to Brazil -- it's an amazing place.

Regarding how to actually get the visa, I've found that you can usually go to a consulate that's convenient for you, rather than to your "assigned region." Nobody has ever asked me to prove that I'm a resident of a certain state and if really pressed you could say that you are on vacation. There is a consulate in San Francisco if that's easier for you than LA.

If you ask a friend to go for you, perhaps you could save him a trip by printing the forms beforehand. Try this link:

http://www.brazilhouston.org/ingles/visaform.htm

Hope this helps. Have a great time!