I buy from Arc Euro, fewer duds! A non-obvious reason perhaps, is the limited range of inserts Arc stock are a good match to hobby requirements. ebay, and other suppliers, often carry a much larger range useful to professionals, but are liable to disappoint a beginner who can't use them properly. Hobby kit is rarely powerful, fast and rigid enough to get the best out of carbide in full metal munching mode. Production machine tools are considerably more powerful, rigid, and faster than ours.)
Talking of improperly using inserts, the non-ferrous type sold by Arc Euro work well on steel at hobby machine RPM. It's to do with their shape and sharpness.
Dave