Some new data, and a nice resource to track pricing trends. Not completely on point, but close enough for government work -
Reduced cell cost suggests the upcoming era of large capacity cells | EnergyTrend
Battery Price | EnergyTrend
If I read their chart correctly, they are pricing $/Ah and the Panasonic NCR18650A 3100mAh cells would fall into the <3.2aH category, with a Q3 estimate of $0.74/Ah or ~$2.29/cell. That works out to ~$205/kWh (for the cells) and a total pack cost of ~$21,000 for the 85kWh pack that I've simulated.
Unfortunately there are many problems with the market price listed. First, it's the average selling price for cylindrical cells in general.
The common 18650 cells are just a subset of the cylindrical cells, and based on my understanding they tend to cost less than the other formats because they are produced in much greater quantities. Thus I'd expect a lower average price for 18650's compared to what is quoted here. In addition, this does not account at all for the many cost saving features of the Tesla cells, or potential discounts because they are the largest purchaser in the world (which they almost certainly are now) or because of the business relationship they have with Panasonic (with Panasonic being a part owner of Tesla). On the downside, the Panasonic NCR18650A cells tend to sell for a higher price than competitors for a given cell size.
With all of the moving parts this doesn't get us anything like firm pricing, but I think it strongly supports the data we have pointing to a Tesla pack cost that is in the ~$200/kWh range. And again, we have many sources mentioned in this thread which have claimed that Tesla would deliver the Model S pack for under $200/kWh. We also have a wealth of other data pointing to that, including the I.E.K. report listing 18650 cell costs in the $120-$200/kWh range at the end of 2012 and the many advertisements on wholesaler websites also pointing to relatively low prices.
Other tidbits in these new links are confirmation of a general slowdown in 18650 production overall thanks to the movement towards ultra-thin devices, with manufacturers being forced to produce low end cells at or below cost. We have academic research pointing to per cell costs in the range of $1.50-$1.80 for the 18650 cells, without factoring in profits.
However, Tesla is now big enough that they appear to be reversing the trend in 18650 production -
Panasonic to increase lithium-ion battery production capacity - BUSINESS - Globaltimes.cn
And we also know that Tesla is also working with Samsung as an alternate supplier. With all of this activity, Tesla is certain to take over an increasingly large share of the 18650 market, and they will do so as other players are exiting the market, allowing Tesla to purchase batteries from existing plants whose costs have already been fully amortized. In the long term though, GENIII requirements will substantially outstrip existing production capacity (which I estimate is enough to supply ~120,000 Model S class batteries if you use a nextgen cell with 4.0mAh).
So we'll get a sense of Tesla GENIII sales expectations in a year or two when the major battery manufacturers start announcing additional production capacity to support it. A likely doubling or tripling of global cylindrical battery production is not the sort of thing that will fly under the radar.