Doorbells. I had to replace a relative’s doorbell recently and the old one that lasted 60 years was built 10x better than the incredibly cheap model that all the hardware stores carry.
The options are either a cheapo doorbell that has an LED in it for no reason, a Ring surveillance doorbell, or a very expensive reproduction doorbell sold on some random website.
Big-o and Little-o notation
FIFO and LIFO