NEX 5 Spare Battery, Sony or 3rd Party.
So far this
seems quite allright.
I had some no brand batteries for several cameras and they all worked good for a much lower price then the Sony ones.
There are some sub stnadard batteries for the Nex5 out there. They are not exactly the right size and will need some stuffing when inserted in the camerato make it work.
But most batteries out there are great and only cheaper...