It works well, if that's what you are asking.  It's a well-known repellent that's been around for a long time.  It is a little bit of work to use it properly as I recall, several steps.

Talk to people who served in her mission to find out more.

No idea if everything that guy is telling you is legit, seems a little shady.  It's not cheap, but I'm pretty sure I paid nowhere near the price you were quoted for a supply that lasts many years.