Why buy it if you can get it free? The department of Chemistry at Case Western Reserve University maintains a Ready Reserve Stockroom of free chemicals for courses and research in the department. The chemicals stored here come from various sources, such as retiring faculty member’s labs and chemicals no longer needed by researchers and courses.
Sigma-Aldrich is one of the major chemical suppliers of general chemicals for synthesis.
Acros is another major supplier of organic chemicals.
Strem is a well known company specializing in supplying inorganic chemicals