How much is the full retail for the 6 & 6 Plus?

[Bimwad]

The only one the Apple Store sells advertises for sale without a contract is the TMobile version

Fixed.

Apple is geared toward selling phones via the traditional contractually subsidized sales model. But that doesn't mean they don't sell unsubsidized, unlocked handsets. They just don't really publicize that fact.

Customers need to know what to ask for ("device only"), and not expect much in the way of support in situations that deviate from the typical ways.