Not sure how long it's going to last, but sales on XQD cards don't come around very often, so I thought I'd mentioned it, even if this does look a bit like click bait.
This site's exclusive advertiser has the the Sony G and M series XQD cards with instant savings from US$11 to US$50 off [advertiser link].
For D5 and D500 users, I would recommend the 32GB G (US$59) or 64GB G (US$90) cards. Those are the right speed to maximize the camera's buffer performance, and I believe the right sizes to consider; putting too many images on one card is a data jeopardy thing, so I tend to avoid the 128GB and 256GB cards, as there's really no need for them with the 20mp cameras. If you believe the rumors that the D810 followup will also have an XQD slot and more pixels and you think you'll update to it, then perhaps the larger cards are worth considering.
Note that the 32GB M card, though tempting at US$40, has a maximum write performance about half that of the D5 and D500. If you're going to opt for the less expensive M series, pick at least the 64GB, which is relatively close to the performance that the twin Nikon pro cameras can manage.
