As I mentioned in another thread, you buy cheap -- you buy twice. Or at least you're taking that chance.
Isn't it better to just spend the money and get what you want than to take a chance on losing money and getting ripped off? Never heard of 300 mgs. As it is, Primmo is a big, thick, kinda painful shot. If Shearing couldn't do it what makes you think these guys can?
This is why I don't gamble. Losing $100 pisses me off much more than winning $100 makes me happy. And there's a better chance of the former.