For a period I was a digital nomad and stayed in a few cities for ~1 month each. Airbnb allowed us to immerse ourselves in the local neighborhoods and get a real feel for the places. If I had to stay in a hotel for that same period I probably would have chosen a different destination.
So to provide some real numbers I just did this with a dishwasher. The circulation pump broke on a 4 year old dishwasher and would cost around $180 to repair but a new one with a 5 year guarantee would cost $350. Given the repairs came with no such guarantee and the price different was not too crazy we just got the new one.
FYI: Prices converted from South African Rand.
A couple months ago I setup an old Android phone to be a 3G hotspot for some ESP8266 devices. It also created a SSH reverse tunnel so that I could access the devices from the internet.
After rooting the phone, compiling autossh & nginx and getting the whole system setup, the phone broke. At this point it was cheaper and way easier to just get a RasberryPi with a 3G dongle. So unless you have lots of the same old phone lying around this can be a lot more work than the alternatives.
Using something like http://janos.io/ may have made things a bit easier but device support was an issue.