Shining force hayjya for gamegear

I bought a bulk amount of gamegear games from a friend of a friend for pretty cheap. Among them is Shining Force The Sword of Shajya. I'm new to Game Gear becuase I just got one. I showed my other friend and he shit a brick and said it was super-rare. Is it? Anyone know the production numbers?
the game is somewhat rare, but it's not the holy grail.

if it's complete and in good/very good condition, it's worth a good bit more.

it's rare cause people who got it rarely want to let it go again, not neccessarily cause of low production numbers.
It's just the cart in the plastic case. It would have been nice to have an instruction manual if it came with one, I believe some Game Gear games had them.