Thing is, you don't have to buy the Base Game and all the DLC at once. I bought the Royal Edition, but the Base Edition would be cheaper, and you can always buy the DLC the Royal Edition comes with separately. Also, if you're low on cash, wait for Paradox's occasional everything-but-the-kitchen-sink sales.It's honestly not the worst Paradox Games in that regard... For the simple reason it's still early in its life.
With all their DLCs, EUIV, HoI4, Stellaris or even CK2 are by far more expensive.
Hell, the only game that I see as cheaper compartively is Imperator Rome and that's because development for it stopped pretty early.
That's what I did with CK2. I bought the plain vanilla Base Game, and played the hell out of that for about a year.
You don't have to buy everything all at once.