You are not buying a proper copy of Photoshop from that mob.
Photoshop is an incredible piece of software and worth every single cent they ask for it.
An alternative is PixInsight for astrophotographic processing, or, you can download The GIMP (
www.gimp.org) for open source free software which should do most of the things Photoshop does. It's not the same, but, it's free.
H