Being from Argentina, where the situation is similar to Brasil, I agree with deranged coder. Ask which parts of town are dangerous and which are safe and absolutely avoid the dangerous ones. Try not displaying expensive equipment in public, do not leave valuables inside parked cars. It is not as bad as it may seem, if you are sensible and a little bit carefull you will not have any problem.
As to the flashlights, I can assure you that hardly anyone down there knows that a flashlight can cost more than $20...