Picked one up last night. $10 is still about $5 too much, but what the hey. Error is listed at +/- 5%. I put it in my desktop humi and checked it after a couple hours and it had settled to within 3%, so it seems reasonably accurate for the price. I haven't had a hygrometer for the last few years, I go by feel and "smokeability". I also periodically check my RH with a $$$ hygrometer (+/- 1%) that I borrow from work. I guess if you like toys this is a cheap, reasonably accurate unit. I sure as hell wouldn't pay $20 for it though.