This topic keeps coming up. So, you can search the board for many more threads like this.
I don't get excited about specialized tools. I have a rotary cutter and board, a ruler, and the Starmaker 5, 6, and 8 for the angles needed to make a 5, 6, and 8 pointed star. I also have a ruler with curves, but haven't used it since the class I bought it for. I could see buying the wedge and pattern for the spiral quilts, but they could also be done with a template.