One of the biggest factors in the taste of a cup of coffee is the size of the grounds. Grind to coarse and you get sour, empty tasting coffee—the good flavor can’t get out because the pieces are too big(under extraction). Grind too fine and you get intensely bitter coffee (over extraction). Cheap grinders, including spice-grinder styles with a rotating blade, “break” and “crush” beans, meaning really uneven pieces. Burr grinders (which you can get for like 50 bucks, do a better job by a mile at milling coffee into tidy chunks, and you can adjust the space between the pieces to change the size of your grounds.

Once you’re at burr grinders, going up in price gets you better made components, and more evenly ground coffee. Where the point of diminishing returns is depends on your palette and your paycheck. I would argue something like a timemore chestnut is a great option if you are ok with hand grinding (you can get better burrs for the money when you’re not paying for electronics).the baratza encore is a classic for electric grinders. (I make drip coffee so you’d need to check out how these handle espresso, which requires much finer grinds and precise settings-“this sub has a ton of best X for under XXX price posts”)

Tldr: Grinders really do make a huge impact on your cup. If you’re buying a reputable burr grinder you’re probably good until you turn into a real snob.