Could be in triple digits. Did you check the listings at Gunbroker to get a sense of where your gun fits in?.
There is one listing for a NIB Supermatic Trophy. Asking $969.00. No bids.
It is an original H-S, yes? Problem - the gun listed above has a serial number lower than yours (30740). It was made in the East Hartford factory sometime after March 1973. The East Hartford guns are, frankly, less desirable than guns made at the Hamden factory. High Standard was in decline at that point and the guns - though many are good - have a reputation for spotty quality.
There are lots of very nice Supermatic for sale. Many of the 98%+ are about $1000. But no one is bidding on them at that price. So.....are those guns worth $1000? Is yours worth more? BTW.....its is hard to call a gun that is as old as yours "New In Box". More properly it is "Mint, unfired, as new". It is certainly not "new".