I've come across a used penis enhancer in the toy section once, a vaginal rejuvenator medical device, and a BDSM whip, but the fake breast is up there. You really never know what you'll find in thrift stores.

I had my own stockpile of free Nerf guns, naturally including the huge sniper one that is hard to hide in my apartment (sorry ladies). They look so cool, so they're hard to want to sell. I found them with their ammo clips and drums. Those are often worth more than the damn guns. The best one I found was a motorized one, but I sold it.