I just bought the cheap ones and I have a new OEM. I'll try to pay attention, but lithium ion degrades with cycles, not really time. Its not lead acid or traditional chemical reaction energy storage, same rules don't really apply.
Sort of think of it like this: miles on a vehicle in a city vs highway.
It's the cycles (miles) that matter. It's going to get much more technical if you dig deeper. The cheapos will have less mAh milliamperage (1000-1300 or less on the NP60s) vs OEM (1350+) so shop for that. As far as who builds it and if it makes a difference - I'll defer to the other folks who commented. Lets just assume, void of starting an interstellar war, that a majority are manufactured in a certain country and the OEM is manufactured in the same country (I just checked).