How much does it cost to make a notarized letter and what documents do I need?

I don't have any letter, I have to make a letter here and note it with you, that's called a power of attorney

If your question is about a power of attorney to be represented in Colombia for a procedure, an authentication or signature recognition would be done, you must bring the document you want to authenticate. Your citizenship card and a money order for U$24 can be presented at the consulate for this process between 08:00 am and 02:00 pm, Monday through Friday.