According to various user reports, it seems that some customers were suddenly being refunded for their purchases completely out of the blue, despite the controllers allegedly having been shipped out. Valve later confirmed that they took more orders than they could fulfill, and as a result, not all customers would be able to get it.
The bad news is that because Valve is simply trying to unload its existing inventory, and with the Steam Controller being discontinued, it means that Valve will no longer be producing additional units, so if you missed out on the sale, it looks like you’re out of luck. If you were also one of the unlucky ones who got refunded, then that’s just too bad.
That being said, you could probably still find these controllers for sale on eBay and other third-party websites, but there is a chance that they’ll be considerably more expensive and also they might not necessarily be in perfect mint condition.