Good buy or not?
Well done. A life time supply.
And apparently, according to the nice lady at eh Amouage counter in Selfridges, its been discontinued. She mentioned that it might be brought back for Christmas as a "special" but it would no longer be sold as part of their regular line.
So really, its double well-done on your find!
... and you only use a single drop or two at a time, since it's an attar. Very concentrated, hence the value.