As far a civ5 addons, I usually wait for the steam sale bc $30 is rediculous for extra features which dont really add awhole lot to a game like that anyways, more like extra things to deal with.
Ive been successful waiting for sales for these things, I recently grabbed the season pass from steam for borderlands 2 for $10 a while ago.
I dont think I ever bought COD packs, if i did its been a real real long time ago in MW2. I did get bf3 premium for $20 at xmas that was cool alot of extra content that was worth it.
Also alot of the time when a game goes on sale, the addon stuff is also on sale and/or sold together as a bundle for cheap on steam, I usually just try my best to wait till summer sale and the holiday sale on steam and clean house.
