Yup, at full price Stellaris is unreasonably expensive and you really want to be picking it up on sale. On sale getting a "complete" version will run you somewhere in the neighborhood of $100, which is still quite pricey but reasonable if you're really into the game. For a casual player just getting in, I would definitely advise sticking to the base plus Utopia plus maybe one or two others that look interesting to you, and you can keep the purchase price to under $30 on sale.

Generally the DLC's go on sale 8-12 months after they are released, and it's often prudent to wait for this because the DLC is very expensive at full price for how much content is actually there.

In the news: https://phys.org/news/2021-02-quantum-entire-radio-frequency-spectrum.html
"""
A new quantum sensor can analyze the full spectrum of radio frequency and real-world signals, unleashing new potentials for soldier communications, spectrum awareness and electronic warfare.
"""

-> spies don't sleep either

Edit: typo

Indeed. In the real world, agencies that neglected HUMINT have paid for it already
The game is very good even without DLC. If one likes it and eventually wants to see and do new things, there are DLC to add more. Rinse and repeat and the game stays afresh. Eventually, adding more and more DLC changes the game into something rather different than it was originally. That seems to be a sensible approach.