I'd like to add...

If the bank teller cash withdrawal isn't a viable option for you because you don't have a bank account, there's another simple way to get cash - send it to yourself! I've found that Western Union has low fees and very fair international exchange rates. I once sent myself nearly $5,000 in 6 separate transactions of less than $1,000 ( each transaction under $1k to keep the fees down and prevent me from having to fill out special tax forms). It only cost me $195 to send the money BEFORE my trip, and it was ready for pickup when I landed in my destination country. Western Union locations can be found in practically any country - at a currency exchange, gas station, or Wal-Mart.

And no, that's not a shameless plug for Western Union. I'm just speaking from experience.