They are cheaper if you buy them on sale. And even more so when they once again sell them all together on humble bundle.

The achievement "Live long and in peace" has a translation error.
In German it is called "Lebe land und in Frieden". The error is in the description. It says "Besitze 30 wohlständige Staaten..."
Instead it should say "Besitze 30 wohlhabende Staaten..."
The noun is "Wohlstand" but the adjective is "wohlhabend".
I hope you include this in that next awesome looking dlc of yours^^