Timely thread-bump, was having dinner last night with people who actually know something about these drugs (as opposed to those who just take them). The topic arose 'cos one of our friends had attended a hen's party where at least one of the botox'd attendees was shooting one of them up; our friend is diabetic (the type you're born with) so knows all about injections, and was horrified about the lack of care about injecting bubbles etc, but that's not the topic of this ...
So these drugs DO have some nasty side effects, on top of nobody yet knowing what long-term damage they may do. If anyone's selling them as being a side-affect-less miracle cure they're a full-on scam artist. Also there's a technical limitation on the amount that can be manufactured - it's one of those "not enough X in the world" things, and all the fadsters buying it illegally is pushing prices up & availability down for those who most need it.