The Nikon NIKKOR Z 100-400mm f/4.5-5.6 VR S lens is currently 8% off at Amazon only ($2,495 instead of the regular $2,696, shipped and sold by Amazon):
Update: the deal is already gone/sold out.
The price at B&H and Adorama is $2,696.95 – $200 more. Amazon has done similar flash sales in the past – they are legit and last only a few hours.
Also – the Nikon EN-EL18D battery for Z9 is now on sale for $149 everywhere: B&H | Adorama | Amazon.