ABF: Any idea what this game is worth?

[Weltall]

I found this gem at Goodwill and it immediately occurred to me that it might be severely undervalued being a Sid Meier's game in the old big box. I don't know if there is supposed to be a full manual, but there is the install guide and reference card. The disc is in perfect shape, no scratches or flaws.

I looked on ebay and Amazon and see the game in just a jewel case or sleeve for $30-40 so this should logically be worth more, but I can't find a listing for the boxed version. I know you are an aficionado so you may have an idea of its value. I have better photos on my camera but I'm out of town at the moment.

Thx btw