I have a 200 EUR handgrinder and an Aeropress. That's about the limit for me, there isn't really anything else to improve there for filter coffee. There's probably a lot more ways to make different coffee, but not that much room for making the same coffee better. I also don't want to mess with the water, so that puts a ceiling on coffee quality anyway.

There's some legitimate room to spend much more money when making Espresso. But a lot of the more expensive options would be more about the workflow than quality. If you need to make many Espressos in quick succession you'll hit the limits of cheaper equipment.