The Noreve case for the Oasis is now available. For most people, this case has a fatal flaw in that it doesn't charge the Oasis. Also, few people (if any) are going to pay $289.99 for an Oasis and then $54.48 for a 3rd-party case. So, I mention this case only to expand the list FWIW.
http://www.noreve.com/en/kindle-oasi...ther-case.html
EDIT
I looked through the photos on the Noreve site and it appears that you can insert the Oasis into the Noreve case with or without the Amazon case. This deals with the charging issue, but I can't imagine who would want to carry around an Oasis in two cases.