I use the Ofna tire truer, and think its great.
The first day I bought mine, I spent about 6 or 7 hours just trueing a stack of tires that I had built up.
When your blade goes dull<and they will> use a hack saw blade, or a sawzall blade and make your own blade for the machine. They are a fraction of the cost, and you can choose how many teeth per inch on the blade your are going to use.
Be sure and use an AC adapter instead of a 12 volt battery, because the batteries will go dead fairly quick.