Ehh, it's still sealed. Sealed games typically bump the price of a game up quite a bit, especially when it's hot.
Go see how much a non-Greatest Hits verison of Metal Gear Solid or Final Fantasy VII costs when still sealed and get back with me.

(hope you have a few $100 bills handy). Ditto for a Chrono Trigger that's still sealed (hell, look at how much the game goes for when it's not sealed but has the box, manual, and map (protip: Expect ~$120 or so). Sealed? About $300+
That's just the way the collector's market works *shrug* High demand out of print games, regardless of rarity(lol @ Chrono Trigger and Earthbound being called Rare) command a pretty penny when still sealed up.