an arm and a leg vs lavish

an arm and a leg

noun
  • Usually used after the verb cost, but also often charge, pay, and spend: a very high price for an item or service; an exorbitant price 

lavish

verb
  • To give out extremely generously; to squander. 

  • To give out to (somebody) extremely generously. 

adj
  • Superabundant; excessive. 

  • Expending or bestowing profusely; profuse; prodigal. 

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