InSe, In2Se3, and GaSe are important III-VI semiconductors and are attractive for electronic, optical, and optoelectronic applications. This paper reports a fast and cheap way called combustion synthesis to prepare InSe, In2Se3, and GaSe. Bulk samples with relative densities up to 98% are directly produced in a few seconds. The samples show a high phase purity, correct stoichiometry, and lamellar crystals larger than 100m. By optical absorption, the bandgaps of InSe, In2Se3, and GaSe are determined to be 1.08, 1.24 and 1.75eV, respectively.