Unfortunately, Bungie is no longer selling Forsaken or Silver on the Blizzard Battle.net store. You will need to wait until 10/1 to purchase Silver on Steam. As a workaround, if you have a console with Destiny 2, you can enable cross save to purchase the Silver on the console's store. Once purchased, you can then purchase the OEM ornament while still on the console. Once completed, you can return to your PC with your ornament.