"I mainly want to get a coffee grinder because beans have a longer shelf life and are cheaper."
Bruh...
If that's your goal for now, buy cheapest conical bur you can find (even if you are a hot and black kind of coffee person, there's just no reason to disrespect the beans with anything else). I think your reasons for wanting to grind may evolve with time and you can reassess your goals and options at that time.