I love that ruler. Yes it is pricey. What to consider is if you like piecing those stars with a Y seam. This prevent you from doing the Y seam. It give you perfect points where they meet and perfect 1/4 inch at the end point of the stars so you are not chopping the star points. The question you have to ask yourself is whether you want to avoid the hard way of making those beatiful stars.
I have made over 100 of those stars in many sizes using that ruler and gotten almost to perfect blocks.