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It depends upon how hard core you want to go, I see from the above posts, they are leaning towards the upscale line, completely ruling out the blade units. I'd say, 4 cups a day isn't much, and if you are on a budget, then go with the 15.00 blade grinder, they do the job you just have to watch how long the beans are in there otherwise it will grind it too fine. I've never had a temperature problem with one, ie. getting too hot and burning the beans, if you reach that point, then, hell yes, it's time to get something serious, but at 4 cups a day, you'll never need it. They also leave a bit of grinds under the blade area, again, 4 cups a day, you might as pull the excess from the bottom if you even notice it diminishing the quality at all.
Now, if you decide to make the jump and want to buy "one" grinder that you will use for the rest of your life, then look in the commercial market, in particular what is reccommended for decaf use, this way you get something substantial at the lower end of the commercial pricing, yet using it at home as an "average" user, it's highly unlikely you'd ever have to do anything more then replace the burrs every 5-10 years if even that, the main thing about all of them is to keep them clean to prevent the parts from clogging as well as leaving residue.