Technically two flat stones with coffee beans between them will do the job.
The MDF overheats the beans, the burrs wear out too fast and they wobble, plus the dosing lever and return spring are prone to breaking.
It used to be that one could find a good used espresso grinder for less than a couple hundred dollars. Those days are long gone unless you're willing to be über patient and wait for one to come along and then jump on it!
I figure that with S&H, plus new burrs, a quality used commercial espresso grinder should cost $250 - $300. That's not bad when you figure that, except for replacing burrs every 5 - 10 years, this machine is the last grinder you'll ever
NEED to buy.