My best buy is unmounted rubber. I have 100 sets on my desktop, and my mounted stamps sit unused. My Palette Noir and Brilliance Black inks, Also my tag punches and my ticket corner punch.
My buyers remorse is for my large SU pads. I have 5 colors plus black and never ever touch them. I am a spots girl! (I took out one today to do some indexing- thought it would work better since I was doing so much stamping, and it sags so much in the middle I had to switch to spots!)
I also never touch my perfect pearls. Ever, except the day I got them. And my Palette glue pad has never worked!