From some of the reviews, some people are getting bad batteries.
I have just used my second pair, both sets are working fine.
So far my costs are averaging at less than $1.25 per. This is a great deal.

Followup, It is now 2016 I have used at least 8 more batteries and one other that  failed. So I am happy about shelf life and my average cost per working battery is a fraction of a dollar each.