I personally have never used that particular scale... In my personal experience a cheapy low quality scale will not really be very accurate... With the cheap <$50 scale that I purchased recently I have noticed that sometimes it is waaaaay out...
I guess that at the end of the day it is only $30... I reckon you should just buy it and let us all know how accurate it is

hehehe - Id definitely buy one if it was half decent.

Really though as you become more experienced with any particular batch of spice... you begin to 'know' what an active breakthrough dose looks like... sometimes a trained eyeball can be the most accurate scale