I have the origami case, but prefer a book style case. I have multiple ones and the best are by Fintie and Swees. The Swees case seems very cheap on eBay.com, could you get one from there? I have two of them for the Voyage, the Gold and the Pink so I know they are good.
http://www.ebay.com/itm/Ultra-Slim-B...item35ebd9e203
Fintie are more expensive. I found this listing.
http://www.ebay.com/itm/For-Kindle-V...item25982bb61a
Both Swees and Fintie leave the top and bottom sides open, making them very easy to get the Voyage in and out of. I have the Omoton as well, which is similar to the Moko style (I.e the top is covered) and I hate it, I'd never touch one of those style cases again.