Because it is a glass packed battery.
Also, it is not 60% premium, but 400% premium, comparing to regular led acid battery, that sells, for a good quality one, for around $75 in any parts store.
Also, it is Toyota dealer price.
Alternative batteries, same or better quality, are sold for $180, which is still a lot, but, at least, not $360.
Keep in mind, that replacement battery should not be ordered based on cranking power. 12V battery in Hybrids is not starting engine but, basically, maintaining backup power. It should be geared towards high capacity low continuous charge. Instead of cold crank rating.