big money vs pretty penny

big money

noun
  • A large amount of money, especially a significant source of revenue or income. 

  • Large corporations, the people who run them, or corporate interest generally, seen as exerting political influence and prioritising profits over other political concerns. 

adj
  • Involving or transacting a large amount of money. 

pretty penny

noun
  • A considerable amount of money; a high price or a high income. 

How often have the words big money and pretty penny occurred in a corpus of books? (source: Google Ngram Viewer )