Well real oem cells are inside tool packs and such. I dig in recycle bins sometimes you find brand new display tool packs or returns where a board went bad Or one cell died. Etc but if your in the states imrbatteries, lionwholesale, 18650battery store, if your overseas I’d try nkon.nl
I wouldn’t pay for the price of tool packs just to harvest the cells. If they are free that’s one thing. But cost to much for the cells. For flashlights and vapes b grade cells are more then enough. The only way to get oem cells is to take them out of oem products. A example in a spec sheet a cell might say 18 mohm resistance. Well this batch came out at 25 mohm etc so it goes as grade b for our use will see no difference. But stay away from rewrappers. They buy the cheapest ones they can get low b and c grade cells and then charge a premium. They don’t care if one cell is a 25r and the next one in your pair is a he2 they see it as your still getting a 20 amp 2500 cell.
You can see this in mooches test when the hg2 first came out it was a 20 amp battery. His latest test a few months back has it as a 19amp battery now. The quality has gone down it fluctuates. B1 to b3. The a grade cells go to corporations.