Here and there, you witness transactions made with currency just as strange as the locks of hair at the chestnut stand: toenail clippings, candied beetles, bottled song, vials of tears.

Silk farmer
A spindly man sits cross-legged atop a wooden crate from which loud munching sounds can be heard. The man puts down his cup of berry-infused tea and shows you what's in the crate. Giant silkworms, the size of Berry's leg, chomping on mulberry leaves. The man sells bolts of fine silk. And silk cord stronger than rope. The man only accepts giant dragonfly wings as payment. Luckily, Squiddly knows where to get some, and offers to run to the other end of the market to buy them for you.
OOC:
Giant silkworm rope. 75 feet. 5 lbs. 4 hit points and can be burst with a DC 18 Strength check. 12gp worth of giant dragonfly wings.