Reserve prices added to items, once the reserve has been met any bid uncontested for 72 hours will be accepted. The cape is the equivalent of a 12 attack cape for a warrior, which is valued here at 5.7b. The 3b reserve price reflects the limited demand for a warrior only cape.
Ah good, the reserve price is what I was curious about because like you said, it's way less than a all class 12 att cape. Bit out my price range unless it goes unsold for a bit ;p