I really to buy lots of cases for all of my devices, and I search for the best prices. Here is a look at an Ultra Thin case for the BlackBerry Passport I found, enjoy! Here is a link to purchase, and a video I've done as well.
http://www.amazon.com/gp/product/B00RC1OMO0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
https://www.youtube.com/watch?v=VZo_6T_fvzM