I’ve used a little $20 blade grinder. The difference between it and a $200 grinder was night and day. Then I tried a $400 grinder. It was definitely better than the $200, but the diminishing returns were stark. Ultimately I kept the more expensive unit, though, because it generated about 1/10 the mess, was easier to clean, was faster, and ran much more quietly.

That’s my limit, though. All my research indicates you can get “better” cups by spending (a lot) more, but the difference is slim and possibly nonexistent if you aren’t some aficionado.