I already have a few AW & Nightcore batteries. Just buying a half dozen backup 18650s for long haul trips. What do you recommend?
What’s your price range and when do you need them ?
That might help the suggestions . J) 
For backup and general use, I don't think you can beat this deal.
It’s more of a I want pretty good quality as cheap as possible. I’m OK with snail mail from China. I have enough to get by.
Protected cells are preferred for safety reasons.
Actually, if he has any left, these are an unbelievable deal:
Edit: Just to let you know, don’t dismiss these because they’re used. Here’s what one happy customer had to say.
If you want new ones with protection:
Under 5$ per piece for a Samsung 2600mAh cell
What lights or use will they be for? Do you need button top or protected? Are you willing to wait at least 2 months to get a better deal from china?
Without knowing anything, I suggest:
http://www.mtnelectronics.com/index.php?route=product/product&product_id=168&search=ncr18650pf
If you want protected get Keeppower as Dangerous suggested or Evva from mtnelectronics. Those two are the least expensive with good protection.
I'd suggest measuring your existing battery before buying. That way you can look at the size of what you are buying and know if it will fit in your particular light. Battery sizes differ out there. Ask me how I know...:)
Great Suggestion ! The battery size situation has been
totally overlooked here. H)
the best is to buy a hobby charger like the budget minded REAL imax b6.the fakes are not that much cheaper anyway.
and the feedstock for your new sickness addiction hobby can be free or cheap.cheap 18650
I use these… Evva from mtnelectronics
He is also a forum member so I like supporting him.