Source : Webster's Revised Unabridged Dictionary (1913)

Bargainer \Bar"gain*er\, n.
   One who makes a bargain; -- sometimes in the sense of
   bargainor.

Source : WordNet®

bargainer
     n 1: someone who purchases and maintains an inventory of goods to
          be sold [syn: {trader}, {dealer}, {monger}]
     2: negotiator of the terms of a transaction; "he is a hard
        bargainer"