Electronics lose value on a clock nobody in the room controls, which makes this the easiest category to price honestly and the easiest to over-hope in.
What moves the number
Whether it works, shown rather than claimed.
What is included — charger, cable, box, case.
Battery age and health, where the device reports it.
Storage, model and year.
Whether it has been signed out — a device still linked to an old account is worth very little to anybody. Why that matters.
Why two of the same differ
One seller booted it on camera and showed the settings page. The other wrote "working, good condition". Thirty seconds of a device running is the most valuable thing in the listing.
How to find out rather than guess
Compare completed sales of the same model, storage and state — tested, untested, or for parts. Those three are different markets, and the gap between them is large.
Also check what a new one costs today, because your room already has. You are pricing the difference between that and yours, honestly.
What is usually worth less than hoped
Devices two or more generations old, anything with a swollen or failing battery, and anything that cannot be signed out of its previous account.
Questions people ask
Is a cracked screen worth repairing first?
Usually not, unless the repair is cheap and you can say who did it and show it working after.
What about a device I cannot test?
Sell it as untested, in the title, at untested prices. It is an honest and normal listing.
Do cables and chargers sell?
As lots, yes. Alone, rarely.