I had some problems with the first unit I got. ITead replaced the faulty unit and the replacement works great. I also bought another one that also works fine. I have only tested the units so far, but they seem to be fairly accurate.
I actually got one of the $10-board in the mail today
I haven't had the time to fully test it yet, but the quality seems fine. The only thing I have noticed so far is that the leds are in different colors (power: green, and pin13: red) than my other "fake" board.
It even has the X3 header soldered in, whatever it might be good for...