There may be a place holder that Amazon has up on it. Apparently they haven't received their shipment from Motorola yet on the 16gbs yet.

http://www.reddit.com/r/MotoG/comments/3ezrln/anyone_else_preorder_the_16gb_from_amazon/

There are links to the 16gb in there. Read more for more info.

Link to Amazon listing: http://smile.amazon.com/dp/B00ZQVSKS2

What about this or this. The 3rd generation also has official CyanogenMod support (The 4th generation seems to have some unofficial builds but it's still pretty new).