Well, back in September I bought a 'genuine LG' BL-T9 with tools from a Chinese seller on ebay for $9.
I literally went over it with a magnifying glass and it appears genuine. All the markings are correct, the temp varies, and the build quality is the same as the original.
In fact, the only way I could tell the 2 apart was the sticky residue on the back of the original and the mfg date (11/26/2013 & 07/08/2016).
I took a chance on getting a fake, and if I did it turned out to be a good fake, as SOT went from under 2hrs to slightly over 4 and standby time is almost 5 days compared to the 2.5 or so from the original.
I gambled the $9 and unless my Nexus does a Note 7, I did good.
---------- Post added at 07:20 AM ---------- Previous post was at 07:14 AM ----------
Manufacturing date is important with Li-polymer batteries.
A 3-year-old unused battery will not last as long as a 3-month-old unused battery.
The 'new' 2013 battery may last longer than the used one in the phone, but it won't last as long as a 2015 battery would.
I'd sooner buy a decent generic 2015-2016 battery than a genuine LG battery made in 2013.