I buy Ebay cell phone batteries all the time for family and friends, and with about a dozen or more battery purchases, I can say that all batteries are not equal. A lot of the cheap Ebay batteries have poor quality control on them and usually don't match the capacity or longevity of OEM batteries. They are so much cheaper, though that it's hard to plunk $40 for an OEM one when you can get a bunch of cheaper (and possibly crappier) batteries for a lot less.
Still, Sawyer, if the refurb guys took your battery, isn't it their problem? They just said "we lost your battery. tough luck"? That seems like something that I would spend a bunch of time on the phone arguing with them about. They owe you a battery.