It's, like, $50. When I said "inexpensive," I wasn't exaggerating.
In order of importance for good coffee, are:
- the beans themselves, and in particular, the age and type of the roast. If you're getting French roast (or darker), the coffee will always taste burnt; dark roasts hide many ills, which is why Starbucks mostly uses them. Something like Toddy helps here because once you brew the coffee, the beans stop oxidizing and aging, and you can brew an entire bag at once. Cold brews are often milder and can reduce the bitterness of dark roasts.
- the grind. Again, cold brewing helps minimize the negative effects of an inconsistent grind.
Everything else is preference, or mitigation. Since you can't change the beans, getting a good grinder isn't going to help much, and I'd suggest spending the $50 on a Toddy. It's the cheapest single mitigation with the biggest impact for shitty beans that you can make. It also makes fantastic coffee from good beans and is super convenient.