i paid 400$ per tube or so. theres only 1 left for that price on ebay. theres pairs for 800 though, might be an option if you are considering WA5.
i would not buy the ones for 700+ per tube, but unfortunately, prices will eventually rise to that price. especially considering the western electric 422a is probably better than the metal mullard gz34 which can already sell for that much if NIB.