Spellforce Universe for 5 bucks is a pretty damn good deal. Lotta content for cheap. Not all great content (1st game gets really grindy toward the end) but well worth it overall.
I always have my eye on this one and then have too many doubts about it to buy it >.< Great price though, that'd cost $30 here.
Would I miss anything important if I just got Spellforce 2: Gold for €3.74?
I really enjoyed Spellforce 1 (and 2 as well, for the most part), though that was quite a few years ago. I'd definitely recommend getting it as well for €1.25; maybe watch some Let's Plays or something like that on youtube and see if the Spellforce games appeal to you.