Claiming that there is a colored Shell for every mood, Motorola is offering 7 different versions of this simple replacement cover. The colors are chalk, black, violet, royal blue, turquoise, lemon lime and cherry. The Shells are priced at $14.99 and will ship starting on December 2nd. If you seek more protection for the screen (it is Gorilla Glass, by the way), the Flip Shells offer the same replacement back Shell, but also include a cover that you can flip around the front of the device to protect the screen. Available in the same 7 colors as the Shells are, this accessory is priced at $29.99 each.
Lastly, there are the Moto G Grip Covers. These won't be ready to ship until January, and are similar to the Shells except for the added rubber on the side. This not only allows you to have a better grip on the phone, it also absorbs impacts better for those times when the enhanced grip doesn't work. We don't have any idea yet what these might be priced at, but they will be available in 5 colors, royal blue, lemon lime, cherry, chalk and black.
source: Motorola via SlashGear