noun (n)

• someone who purchases and maintains an inventory of goods to be sold(noun.person)

  Synonym:
  dealer, monger, trader
  

  source: wordnet30
• negotiator of the terms of a transaction(noun.person)

  Example:
  He is a hard bargainer.
  

  source: wordnet30
• One who makes a bargain; -- sometimes in the sense of bargainor.(noun)

  source: webster1913