I bought the Gold Edition of DoW2. Chaos Rising was included.
I just looked it up. GalCiv2 is only $20. I'm pretty sure I can afford both it and Retribution. Good thing I get paid today!
This is all your fault!
If you are getting paid you might as well also get Europa Universalis 3. It's like a history lesson that ends with you conquering the world. Goes from 1399-1820. Basically pick ANY country and just go. The game gives you a 'mission', but there are no penalties for not completing said mission and you have as long as you want to do it.