Do yourself a favor and check out the $100 model from Northern Tools.Everyonce in awhile they send out emails with a coupon worth 20 percent, which basically boils down to free freight. Its far more accurate than the HF model, and has served me well for five years now.Not as good quality of the more expensive model,but if you are just sharpening your own chains and maybe a few for friends, it is money better spent than on the HF model. The plastic chassis of the HF model alone oughta tell you how accurate they are going to be, and when it comes to sharpening a chain there is nothing more aggravating than dealing with a chain out in the woods that has been ground wrong.
There is no reason to spend a boatload of money on a tool that gets used as infrequently as a chain grinder(at least in my book, you need to learn to handfile as your primary way to sharpen) but there is also no sense in throwing away money on pure junk.