If you are in the US, ordering a Mozo case direct from the Finnish manufacturer could be easier, not to mention prices and shipping bring a single case into the $60 range for most. We have known that the cases would seep into third-party retailers (and even Microsoft Stores are reportedly carrying them soon), but for now, you can go to MobileFun.com.
The site looks to have all styles of the Mozo cases for the Lumia 950 and Lumia 950 XL with some 'arriving tomorrow' and others like the red and gold ones for the Lumia 950 on pre-order. Each case costs $44.99, which while not bargain basement cheap when combined with the $2.99 shipping and you can save yourself $15 or more compared to ordering direct from Mozo.
We've been using our Mozo cases for the last few weeks (see our video below) and we can report they are holding up well with no issues to report.
MobileFun.com does not have a direct link to just the Mozo cases, but you can search for the Lumia 950 and Lumia 950 XL ones and find the style you like to order
Overall, it looks like a good deal and hopefully more third-party sites and stores will begin selling these too as they make a big difference for the feel of these phones.
Thanks, Dylan C., for the tip!