I know where you can get some FREE as-is cells. ALL name brand and ALL guaranteed real and not fake. Go to your nearest home depot and look through the recycled battery bin. 
Now the thing is with laptop-pack pulls is that ALL the batteries — without fail — have been EXCELLENTLY cared for. You can’t find better-cared-for li-ion batteries. They have NEVER been overcharged and they have NEVER been over-discharged. Well, you need to check and make sure the batteries aren’t below 2.5 volts from nonuse when you pull them, but the pack electronics will never let them over-discharge. In fact, most packs will refuse to charge if the batteries fall below about 2.5 volts. So as long as you use a DMM to check ’em, you’ll never get an overdischarged cell.
HOWEVER, unscrupulous vendors can “bring back” over-discharged cells. Simply touch a 9-volt power source to an almost dead battery for a few seconds and almost all will pop up to like 2 volts and now can be charged in a normal li-ion charger. BUT since the cell has been overdischarged, chances are that NASTY crystals are also growing when you recharge an over-discharged cell — crystals that will grow and grow and eventually rip through the liner bag inside the 18650, creating the famous “venting with flames.”
Some li-ion chargers will even charge a completely dead 18650. My gray-colored Trustfire charger will charge an 18650 batt at 0 volts. After 20-30 seconds in this charger, most “dead” li-ion battery voltages pop up to 3 volts or so, and the cell can be charged normally.
I am NOT saying that any dealer charges over-discharged cells. I’m just saying that the possibility exists that it can be done, and overdischarged cells often come back with flying colors after being “zapped” and can perfectly hold a charge and charge to full capacity. I have experimented with this and recovered 9-10 cells that were effectively zero volts, and they worked fine after zapping and recharging —— EXCEPT that now they may be growing those dangerous crystals and could vent with flames without warning.
Because of those crystals, you do NOT want to charge over-discharged li-ion cells. This cyrstal puncture can happen at ANY time. The battery can be sitting on your shelf. The crystal can puncture the liner bag when you’re at Aunt Grace’s. The cell vents with flames and burns your house down. (Or causes an airplane to fill with smoke.) Charging overdischarged cells can come back and bite you badly. And unless you harvest the pack pulls yourself, you really have no way of knowing if the pack pulls have been mistreated AFTER being pulled.
Some vendors are beyond reproach and would never intentionally do this. But their supplier could be zapping the cells and not telling them :–0 There’s really no way to tell, and that — fellow BLFers — is the problem. We don’t have x-ray vision and we can’t see inside li-ion batts to see if those highly dangerous crystals are growing.
(I am NOT a li-ion scientist. I am simply going by various white papers that I have read on the web about the dangers of over-discharging. I assume that these papers — like the NASA one on li-ion dangers — are accurate, but I have not done the experimentation myself and must rely on others to do it for me.)