You can buy Silly Putty in bulk. I feel like a jackass for wanting a 5 lb. ball of Silly Putty, but I do.
The good news is now you can buy it guilt free! You can be like my dad. He used to buy us toys for Christmas that were really for HIM (space-age-super-pod-tracto-robotic building sets, etc.). "Merry Christmas, LC! Look! 5 lbs of silly putty!"
When I was in high school (which was fairly recently) someone in my school bought the five pounds and made a small profit selling it off to people. One of my friends ended up with a pound of it, and I can tell you that a one pound ball of silly putty is really really fun to bounce around a room. As long as the floor's clean.