So I was really bored, and started to look into this from the website https://www.celebritytalent.net/sampletalent/index.php?refine=style&cat=american+idol
and you can see how much it costs to book your fave Idols (IDK HOW LEGIT THIS IS THO), here are some figures:
500K - 1M (Carrie)
300K-500K (Kelly)
150K-300K (Adam, JHUD, Daughtry)
75K-150K (Clay, Fantasia, Jordin, Kat Mcphee, Kellie, Lauren Alaina, Scotty, Phillip)
40K-75K (David Archuleta, Scarypoolparty or Alejandro Aranda)
25K-40K (Danny Gokey, Haley, Jessica Sanchez, Laine, Ruben Studdard, Ace Young, Allision Iraheta)
15K-25K (Kris, Trent, Clark, Nick, Gabby, David Cook, Candice, Caleb, Pia Toscano, Taylor Hicks)
7.5K-15K (Crystal, Casey Abrams, Jason Castro, Justin Guarini)