Amzul Rifin Bogor Agricultural University   Agribusiness Departement Jl. Kamper, Wing 4 Level 5 Campus of IPB Darmaga Bogor Agricultural University Bogor, Jawa Barat 16680 Indonesia   amzul_rifin@yahoo.com   http://agribisnis.ipb.ac.id           JEL Areas: D2 : Production and Organizations: General D4 : Market Structure and Pricing: General