Didn't I read that there is a limit of 10 course builder courses per CC ?
There may be not more than 10 Custom Courses in a CC, and they may be built, re-built and replaced for free. "Course Builders" aren't neccessary to build Custom Courses.
"Course Builders", worth 400 cr each, are necessary to create a CC tournament with a Custom Course. I know of no limitation to these - you may try and buy 25 in a bunch ;)