I think you would have to really like it to justify the cost of that. Saying that, people spend more on FIFA players or whatever so maybe it's a steal?

Nah just buy the base game and pirate the DLC lol

Some of them are. IMO the best are Way of Life, Holy Fury, Conclave, and Old Gods. If you want to play some who isn't a Christian King, such as a Christian merchant or pagan/hindu/muslim king, you'll need to get the expansion for that. Respectively, those are The Republic, The Old Gods or Holy Fury (either will unlock Pagans), Rajas of India, and Sword of Islam. That being said, if you like playing a Christian, Sons of Abraham is worth picking up. Finally, if you're the type of person who really likes optimizing these sort of games, then you'll probably want Legacy of Rome, which adds retinues, customizable standing armies that let a skilled player solve the combat system to punch way above their weight

Worth pointing out that for all paradox grand strategy games the dlcs are shared during a multiplayer session. So if you play MP only the host needs to own them.

Some are, some aren’t. Sunset invasion is only really good if you want an alt history scenario with Aztecs invading Europe while other expansions add other religions and types of governments to play.