The Collaborative International Dictionary of English v.0.48:

Freightage \Freight"age\ (fr[=a]t"[asl]j; 48), n.
   1. The charge for transportation; the expense of carriage.
      [1913 Webster]

   2. The transportation of freight.
      [1913 Webster]

   3. Freight; cargo; lading. Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

freightage
    n 1: the charge for transporting something by common carrier;
         "we pay the freight"; "the freight rate is usually cheaper"
         [syn: freight, freightage, freight rate]
    2: transporting goods commercially at rates cheaper than express
       rates [syn: freight, freightage]