The Apple Watch Magnetic Charger to USB-C Cable is essentially the Apple Watch Magnetic Charging Cable with USB-C connector.
It was launched on 19th October 2018. That date also marks the start of iPhone XR’s pre-order.
Unlike the USB-A variant of the Apple Watch Magnetic Charging Cable, which is available in three lengths (0.3 m, 1 m, and 2m), the USB-C variant is only available in 0.3 m.
Regarding pricing, it retails for S$45. It is the same price as its USB-A counterpart.