I think my biggest waste of money would be cheap seam rippers. They are dull and work like cheap seam rippers. Never again. Just pay a smidge more and get a nice one. If I didn't loose them in the sewing room all the time, They practically last forever. And, I truly wish I could just buy another one like the one that came with my sewing machine. I accidentally broke a small piece off. Was the best ripper ever.
Thanks for all your comments. Your saving me money that can be better spent.