You should be able to add an account yourself, no purchase required.
Open phpMyAdmin from the Raspberry Pi desktop Programming menu. Username is root and password is 7388. Open the Users table in the station database. You will see any existing records there. If there aren't any, click Insert at the top. Enter 1 for uID, 1 in Access_Level, your call in MyCall, and admin in Username.
Click Go at the bottom and you will be able to log in to RigPi with username admin and no password.
--Howard