Form me personally, I'd have to say my automated espresso machine. For context; I was buying 1-2 coffees from a shop per day (let's say 10/week on average).
Cost me $700 on a sale. Grinds & presses the beans by itself, then pushes boiling water through to give me espresso shots. It paid for itself in 6 months of ownership by weening me off the local shops, and it's lasted for over 6 years so far.
Instead of ~$4.50 per coffee, it's like $24 for a bulk bag of beans at Costco that lasts me 3 weeks, and a carton of half-and-half that lasts me like a month. That's like $180/mo → $35/mo
Not just straight espresso shots. I drink Lattes and Breves. Typically larges, and truly strong (like 4 shots).
Prices have gone up even, but what I just described costs $8.65 at my local Starbucks. But even the cheaper local shops would charge me like $6 nowadays.
It's ridiculous. I had to cut back on Starbucks (Caribou Coffee). It was that or get a second job to support the habit.
Came here to say this. Wasn't as often but I'd get specialty coffee for $8-$10 a couple times a week. I bought a off brand espresso machine for $100 that is running to this day. If I include various accessories I've probably spent around $200. I did wind up getting a work bonus and splurging on a $400 Eureka grinder so I can have freshly ground.
Last I did the math at most I spend around $1.00 a cup, for a savings of around $8. I've made at least a couple hundred coffees it has definitely paid for itself and then some.
Don't Espresso machines have to be heated up for ages before brewing? James Hoffmann just reviewed one that heats up instantly, and said that the design was revolutionary.
Mine takes a minute or so? I single-dose grind my espresso so by the time my portafilter is ready the machine is ready.