(Image credit: Future) Valve has announced that the next wave of Steam Controllers will only be purchasable through a reservation system similar to the one used early in the Steam Deck's life cycle. The announcement post does not specify when, exactly, this next round of controllers will make it into customers' hands, but reservations are set to open tomorrow, May 8, at 10 AM Pacific / 1 PM Central / 6 PM BST. Valve will open a "reservation queue" at that time. "Once you reserve, your place in line will be saved," the company wrote in its announcement post . "When we go back in stock, order emails will be sent in the same order that reservations were made." Only one per customer. You get three days to act on your reservation once the controller's back in stock. If you already bought a Steam Controller, you can't make a reservation. Your Steam account has to be "in good standing" and have made a purchase prior to April 27.…