Psyringe: GamersGate has the
Crusader Kings II Collection (base game plus most DLC) for 75% off (20 $/€).
This could be the last chance to get a Steam-free version of CK2. Paradox has announced that they plan to discontinue the Steam-free version, and give the people who purchased it Steam keys. Hence I'm buying it now, which will give me the Steam-free version now and Steam keys later.
Caveat: It's a bit of a gamble since Paradox has not stated whether the Steam-free version will keep working afterwards, but I hope there's a way to install it now and make a reusable backup. In any case, if you want both the Steam and Steam-free versions, I'd recommend this deal.
If you have about 60$ to spare, you could also combine it with 3 other games and benefit from the "get 4, pay 3" promo.
Edit: Apparently there's a problem with displaying all the DLC. This collection has 21 DLCs, but some people only see 4. To see all, go to your profile settings and switch "Platforms" from "Automatic" to "All".