The Collaborative International Dictionary of English v.0.48:

Factorage \Fac"tor*age\, n. [Cf. F. factorage.]
   The allowance given to a factor, as a compensation for his
   services; -- called also a commission.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

FACTORAGE. The wages or allowances paid to a factor for his services; it is
more usual to call this commissions. 1 Bouv. Inst. n. 1013; 2 Id. n. 1288.