costing an arm and a leg vs unwarranted

costing an arm and a leg

unwarranted

adj
  • Unjustified, inappropriate or undeserved. 

  • Not warranted; being without warrant, authority, or guaranty; unwarrantable. 

How often have the words costing an arm and a leg and unwarranted occurred in a corpus of books? (source: Google Ngram Viewer )