One thing that stands out on the buy-back scheme is that Telsa might be in a good position to recycle/recondition the battery units for far cheaper than it costs to manufacture them initially.

I'm not all that well-versed on the chemistry of the LiIon tech they use, but other battery chemistries (lead-acid, especially) are reasonably easy to recondition.

Anyone who knows more want to chime in?