Brazil for Americans

If you get it in US:
Takes 10-20 days
Costs $200-$300
Usually multi-entry for 5 years.
Requires bank statements, vaccines, knowing where you're going and buying your tickets first.

In Buenos Aires:
Takes 2 days
Costs $250
90 day visa.
Requires same as in US but you also have to make an appointment ahead of time and fill out online application and bring it in.
Hours: M-F 9-13(1pm)

In Montevideo
Takes two days,
Costs $160
Five year visa
Hours M-F, 9-15 (3pm)
Same requirements as Argentina, but more relaxed.

In Chuy:
Takes about an hour and a half.
Costs US$160 (in Uruguay pesos)
Ten year visa.
Just need a bank statement.
Hours: M-F, 9-15(3pm)
Getting to Chuy: $25 bus from Montevideo, 5 hours.
Consulate directions:
From the bus stop, walk straight and make a right on Brasil St. Walk straight four blocks and make a right. Consulate should be on left hand side half a block down. You'll see the flag.

After getting the visa take a cab to the Uruguay customs: $80 pesos (there and back) (8 reals). Bring your bus/boat ticket from Argentina in case you came to Uruguay that way.
Cab to Brazilian side should be $120 pesos (12 reals) there and back.

Getting out of Chuy
Bus Station is in same direction as Consulate but two blocks down make a left and walk two more blocks.
Buses for Puerto Alegro leave every day at 11pm and 12pm.
Buses for Florinopolis leave Sundays at 12pm. This gives you an opportunity to back track to Punto Del Diablo or Punto Del Este for a night.

Buenos Aires to Montevideo via Colonia Sacramento

There are a few things to keep in mind.
Change your money in Argentina! In Uruguai your official dollar from the ATM becomes half price so you loose half your money!
Also, don't take the Boque bus all the way to Uruguai. You can buy a ticket just for the boat ride to Colonia, spend a couple hours there and then buy a ticket for $12 to Montevideo. Buses run every half hour or so with many direct buses. This is cheaper and offers you a way to see Colonia. Bus station is next door to the ferry terminal.
Finally, do not exchange money at the ferry terminal. You can get 10-25% better exchange rate a short walk way at the bus terminal or many other places in the tiny town.

Hope this helps!