like John, I also carry a few sample chips...
At one local sale, I asked for poker chips and the couple give me a blank look and shook their heads. I produced a few old chips (I usually carry an inlaid and illegal) and suddenly the wife said,
"Honey... go grab that old set we have in the garage."
Apologizing to me, she explained the rack was imcomplete because the mice had chewed them up
She charged me $8 for the rack - which was probably 98% complete/ 10%-15% went into the trash and the rest got a rinse in anti-bacterial soap so I wouldn't get the Hanta virus

I also make it very clear that "partial sets" are great since I'm most likely to break the set anyway

Here's one of the chips in that rack (have traders in red-white & blue) ... REAL HHR's!!