For my single user instance, I can be charitable and say that it’s running on hardware that I already had that is running regardless on spare otherwise unused resources with a already registered domain so the only cost is time spent setting it up. Or I could apply all the costs from the server Lemmy, then it would be about $1200 initially plus ~$10/mo per user.
My pixel 6 is about 3 years old and the only wear I can see on it is a single little micro scratch in the top right corner of the screen that I can’t see without a light reflecting off of it. I don’t bother with a screen protector, just a thin silicon case. Battery is fine for about 2 days of normal use even though I regularly use a wireless charger.