Does anyone use these? If so, has anyone used cheap ones? There is one up on craigslist I'm looking at, and for the price I wouldnt' care too much if it was slightly inaccurate (I expect it to be), but want to make sure they're not total crap. This is a link to the one he is selling:
http://www.sportsmansguide.com/cb/cb.asp?a=169416