You can now preorder the Nikon Keymission 360, directly from Nikon. If you order before October 22, 2016, you will get a free KeyMission Accessory Pack that includes a tripod, extension arm (handle / selfie stick), carrying case, and rechargeable battery. Here is the link!
Also available from B&H with free 2-day shipping (double-check if free shipping is available where you live) and from Amazon with Free Prime shipping. Depending on where you live, you might not need to pay a sales tax with one or the other. I’ve confirmed with B&H that if you order with them, you’ll receive the free accessory pack as well.
For Amazon, I haven’t gotten confirmation about the free accessory pack. I’ve confirmed that Amazon has the free accessory pack as well but you have to choose the “accessory bundle” (see link above).
At $499, the Keymission 360 is more expensive than the Samsung Gear 360. However, if you include the value of the Accessory Pack, it decreases the effective cost.
since the preorder offer is until October 22, 2016, it may mean that the Keymission 360 is not shipping until after October 22. The release date is October 26, 2016