In AZ, all seven clubs are members of the Arizona Interclub Association so there is no fee for taking a test at one of the other clubs if you are a member of a club in the Interclub. Handy, because two of the clubs have test sessions every 28 days and the others have additional test sessions throughout the year.
If you are out of state (or not a member of one of the clubs) the fee is $35, and you must have the letter of permission from your club attached to the application. I don't think it has to be specific to the tests, but it does have to be specific to the skater, the club hosting, and possibly that session's date.