at a premium vs sufficient

at a premium

prep
  • At a high, or higher than expected, price. 

  • Scarce, in short supply. 

  • Above par value. 

sufficient

adj
  • Possessing adequate talents or accomplishments; of competent power or ability; qualified; fit. 

  • Of a type or kind that suffices, that satisfies requirements or needs. 

det
  • A quantity (of something) that is as large as is needed. 

  • An adequate quantity of; enough. 

How often have the words at a premium and sufficient occurred in a corpus of books? (source: Google Ngram Viewer )