Grench,
Just guessing, but tell me if I am off base.
The 2015 Turbo X has the same battery, motor, and mechanicals as the 2015/16 base Turbo. It just has the suspended fork. Since the the base Turbo went from $3800 down to $3000, if the markdown on the 2015 Turbo X goes from its 2015 list of $4000 to $3200, they are probably passing factory discounts on to the consumer. Likewise, the 2015 Turbo S has pretty much the same battery, motor, and mechanicals as the 2016 Turbo X (priced at $4500). So if the 2015 Turbo S are marked down from $6000 to around $4500, a similar value equation applies.
Doug