i'm surprised that it's that high for a deck (FYI curiosity got the better of me, AmazonUK is even higher than US version)
i have the OOP Holy Grail deck that someone said was worth 150, yet when i searched both eBay and Amazon was roughly about $45.
i would suggest taking what you paid for it and times it by two, but make sure to take into condition of deck. whether or not there's a box, extra cards, and booklet that came with it. if in mint condition twice what you paid for it is reasonable if OOP. everything else is pretty relative. also depends upon how bad someone wants that deck.