There is more that just one "original" game GalCiv.
The true original was written for OS/2. IMO you're asking for the windows GalCiv and its expansion. For that version I'd say it is worth 99 cents. If nothig more, then just to see how much the game design and AI has evolved. Game is still playable (heck, I finished one about a year ago on my very old portable), but I wouldn't return to it - the AIs play too much by their own rules.