The first thing to know is that this wasn't purchasable from the Google Store. It was actually available from the Power Support website, the company that makes the mount for Google's Stadia controller.
Word seemed to have quickly spread that it was up on the company's own website for $15. And in less than 24 hours all of the company's stock was completely depleted.
The Stadia CLAW may be sold out now, but more are coming
You may have missed out on the CLAW mount this time around. And, if you were planning on playing games on Stadia via your Pixel phone that might be a bit of a bummer. There is good news though.
The CLAW mount is not gone for good. The Power Support website for the mount lists that the initial stock is gone, but that it has more on the way. Google's own store will also have stock eventually. Though when is uncertain at the moment.
The Google Store still shows the CLAW as coming soon, so the company may not have an actual release date set yet. It's also possible that it ran into trouble with the amount of stock that Power Support had on hand. Which seems likely given the company sold out of its first shipment.
The CLAW was highly sought after
Regardless of the number of mounts in the first shipment, it was highly sought after. Selling out is proof of this. Unless Power Supply only made around 50 units, it's likely that users across the globe wanted it.
The Stadia subreddit was filled with posts and discussions about the CLAW even before it was official. Comments flooded the threads asking when or if it would be available.
Of course after Stadia launched and Google confirmed the CLAW would be coming, people started eagerly awaiting its release.
Some users were so excited for it that they went so far as to 3D print their own CLAW mounts to serve the same purpose. This does little to show how many people are actually using Stadia at the moment. But, it does illustrate to some degree that there are probably a lot and that many of them were excited to play games on the phone.