I am sure if it is at AA there asking a arm and a leg for it. nice store to check out but i don't buy from them, there fish and supplies are way way over priced
if you want to drive all the way to appleton, Just Pets as a small silver aro its like 2 3 inches for 48.99 its in really good condition, but thats if you want to make a 3 hr drive.
15 minute walk from Navy Pier? i don't think youll find any. Old Town Aquarium is pretty close and they might have it. Its on Wells, just south of North ave.