Just some of the Research im doing mate. im was looking on doing a cycle of it, the guy I get it from only dus the 10ml bottles. But like you say it's not true that it only comes in 1 amp vials.
The reason you hear that is because Sustanon is a brand name from a company called Organon. They only package in amps not vials. So the companies that copied Organon will call it "Sust" or "Sust250" and put it in a 10ml vial. It doesn't mean it's fake it's just not the original Organon Sustanon.