Hermit Crab Shell Lot

There's been a lot of activity at my shell lot. Right now I have only two shells left, plus several traded in shells. The trade ins are in bad shape, holes, discolored and worn out. The magpie shells were lined up by size and are marked K-1 to K-7 with pink nail polish.
My first customer came, picked out K-2 and left. Next thing I know he came back and left with his old shell. Then not much later K-2 was gone again. My customers are very disorderly, they leave their old shells all over the place and can't seem to make up their minds. I am feeding them stale tortilla chips, K-1 was caught coming back to the lot to nibble on chips. This hermit is huge, not sure if I can even find a shell large enough for its' next trade in.