When you're ready to take the test, the Council says:
"The cost of taking the tests can vary by state, province, or program (collectively known as "jurisdictions"). Some jurisdictions offer the tests for free, while most charge a nominal fee to cover expenses of operating the testing center. Find out how much the tests cost by contacting your local GED testing center."
The Council also notes: "The GED Tests cannot be taken online. The GED Tests can only be taken at an official testing center," so beware of any websites that claim to offer the GED online.