Art yarn is handspun yarn that has no interest in being uniform. Thick and thin. Coiled, looped, locked. Silk buried inside wool. Beads spun directly into the ply. The result is a skein that could not have come from a machine and could not have come from anyone else.
A drop spindle costs less than a skein of luxury yarn and fits in a coat pocket. The fiber, raw locks, dyed batts, blended rovings, is where the real decisions happen. Color, texture, density. All chosen before a single stitch.