NEVER change money with someone hanging around a cambio. They are only there for one sole purpose; to rip you off!
This can not be emphasized enough. Only use a cambio, cash machine or bank.
The rule of thumb is, lay out all the clothes and all the money you are bringing to Jamaica. Now, put away half the clothes and get twice the money. Jamaica soon come, money soon go.
Sing unto God, sing praises to his name: extol him that rideth upon the heavens by his name JAH, and rejoice before him. KJV Psalm 68:4