an arm and a leg vs inexpensive

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 

inexpensive

adj
  • low in price 

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