How do I get power of attorney over my sick grandma without it costing me anything?

Talk to your doc. Power of attorney in regards to health care decisions is a document expressing wishes and limitations by the patient and granting the agent those decision making ability. It needs to be signed by a patient who is of sound mind and understands what it means. It also must be signed by witnesses. An attorney is generally not needed unless a special situation exists. Talk to your doc or hospital.