The publication of Half Life: Alyx, the new title in the Half Life saga for VR, and if you don't have a viewer available yet, this could be your last chance before that date. Valve it has in fact supplied its warehouses with Index VR kit, gone sold out a few days after the announcement of the game.
Orders for Index VR have been available again since March 9th, and immediately shot to the top of Steam's sales charts. Valve has stated that any order that will satisfy any order that exceeds the current availability when new stocks arrive.
The Index Kit costs € 1079, and includes the headset, controllers, base station and a copy of Half Life Alyx at the time the game is released. The supplies however also include the simple viewer and the controllers. You can order the viewer on the appropriate Steam page.
As specified in the product description, the orders will not be anyway shipped before 8 weeks, ten in the case of the Index Kit. Even if you purchase the viewer immediately then, there is the possibility of not having it available until just before Half Life: Alyx is published.