Here's a quote for you if that helps:
“You’re starting to see some schools that are including these same liquidated damages provisions that you see in a head coach’s contract in assistant coaches’ contracts as well, to try to bind those assistant coaches so that if they’re good coaches and good recruiters, they don’t leave,” Reale said. “Or at least if they leave, it’s going to cost the new school, the new employer sometimes a very considerable six-figure number to hire a new assistant coach.”
That's from Jack Reale represents a handful of ACC/SEC coaches as well as some NFL guys, I'd say most notably Champ Bailey. HC buyouts get tossed around all the time because of the $$ figure attached to them but they have long been utilized. **** some places even put a non-compete in that states you can only change schools for a promotion and not a lateral move.