I suppose a "bargain bin" hire is more of a reflection on the overall return of the investment in the coach hired, rather than what is actually spent to bring in the coach in question.
For example, to me, the Kiffin hire was a bit of both. His record was an improvement over 2008 and he had restored hope to the program, but his immaturity was a distraction and the way he did things often left people scratching their heads.
Dooley was the perfect example of a bargain bin hire, nothing else needs to be said (except, perhaps, that the bamboo needs watering and shower discipline is strong).
Butch is a interesting case. He came in with a good resume (strongly constructed by Brian Kelly), but also showed improvement in his first three seasons. The fact that Tennessee faded down the stretch in 2016, plus the debacle that was 2017 (along with Butch being Butch) perhaps exposed the real Jones and therefore finished him off.
And now we have Pruitt. Man, did we want to believe he was the one. In the beginning, he sounded like an SEC coach and had the resume and rings to suggest that his time was here. The wins in 2018 over Auburn and UK (remember, the Cats were good that season) showed potential. Then...Georgia State happened. Arguably the worst loss in school history (Chattanooga 1958, North Texas 1975, Rutgers 1979, and Wyoming 2008 are debatable), followed by a give away loss to BYU opened up the debate. Then...an 8-game win streak over two seasons quieted some of the noise (extensions to Pruitt and Fulmer notwithstanding). Then...a six game losing streak followed, featuring some of the worst football many Big Orange fans have ever seen their team play (along with other distractions). At this point, I'm not sure what category Pruitt's hire falls under...bargain bin or roller coaster. I suppose a bit of both.