There's not much you can do when someone can't, or won't, spend the money necessary to make good top quality coffee. Since consistent brewing is so dependent on particle size, this type of grinder will always disappoint an experienced specialty coffee drinker.
But that's probably not who's buying the grinder, is it? Freshly roasted coffee that's ground just before brewing, is going to taste so much better than what the noob's used to, so I suggest not obsessing about grind quality at this point. Teach them the value of fresh roasted coffee and the need to grind it just before using and you'll be a hero to them.