Apple watch series 4
Why can’t I buy an Apple watch series 4 anymore?
Apple Watch
Question marked as
Because Apple replaced the Series 4 with the Series 5.
You also cannot by the original Apple Watch, nor the Series 1, nor the Series 2. But then again the models that replaced them are more capable, so all is good.
If you must have a Series 4, then check to see if any physical stores have inventory they will sell you, or check on-line stores, such as Amazon.