Purely on the coffee note: freshly grinding coffee is by far the best $-investment vs quality-improvement you can make. A $10 (or cheaper!) blade grinder make

Purely on the coffee note: freshly grinding coffee is by far the best $-investment vs quality-improvement you can make. A $10 (or cheaper!) blade grinder makes a noticeable improvement over pre-ground for nearly everyone, and you can absolutely just stop there and enjoy the step up and that grinder will probably last as long as your drip machine. Very little after that will achieve such a large improvement, and no matter what it'll cost a lot more money and time (e.g. to find and buy better coffee beans).