I've been DIYing my ... off this weekend and to round it off. I had an old laptop battery for a notebook that I no longer have so I whipped out my knife and Leatherman. And boom 9 free 18650 batteries. I haven't used them for sub-ohm vapping but they've been working fine on 1.5ohm coils and all my 18650 flashlights. I nearly chopped off a finger opening the case but it was worth it if nothing more then having a few extra/spare flashlight batteries.
Edit: I did some google searching on the info printed on the battery these turned out to be 2250mAh IMR Panasonic batteries. I may have to start searching Craig's list for old Sony, Samsung, Panasonic, etc Laptops and or laptop batteries. Especially since I've got batteries sitting in Hong Kong for over a month now from FT.