These are the discontinued products currently on my radar. I've been having the most success finding these at older Ace, Do it Best, True Value, and independently-owned hardware stores along with small-town grocery stores that still have old inventory sitting on their shelves.
The key is hitting stores that don't turn inventory as quickly as the big chains. These smaller retailers often have stock that's been sitting for months or even years which means discontinued gold just waiting to be discovered.
(Even if you don't have these stores around you or can't find stock locally, set Keepa alerts. You never know when Amazon will find a random box in the back of their warehouse)
Here's what I'm hunting for right now: