buy up vs expend

buy up

verb
  • To buy the whole of; to purchase the entire stock of something. 

  • To buy off; to pay in blackmail money or similar. 

  • To buy whatever is available of something. 

expend

verb
  • to consume, exhaust (some resource) 

  • to spend, disburse 

How often have the words buy up and expend occurred in a corpus of books? (source: Google Ngram Viewer )