HTC has launched their online Vive Accessory store. You may now purchase some replacement parts for your Vive, with the focus on parts that may wear or become "gross" after use.
The HTC Vive Accessories site will sell "Cables, controllers, headphones and more for your Vive." However, at this time the items for sale include the Nose Rest (Set of 3) for $12.99, Face Cushion (Set of 2) for $24.99, and the USB extension cable for $10.00.
What If you're on the Oculus side of the camp? Currently, there are no replacement parts you may order, only if a part needs replacement will you be able to get hold of one via an RMA.
See Also: Oculus Rift Replacement HDMI Cable