My best purchase: my kit and first order as an SU demo... ink, paper, embossing powder...
Worst: my Cricut. Not because it is a bad product. I am sure it is great. I bought it 6 months ago and it is still sealed in the box. Imagine how much SU stuff I could have purchased instead! Other worst: decorative scissors, for all the same reasons everyone else said. Now my kids have fun and I pick up the little pieces of paper (cheap Michaels stuff) every day.