Buying second-hand electronics - what to look for

[shelivesthedream]

My iPhone 4S is seriously on its way out. The speakers and headphone socket don't work, the battery life is beyond pants, and sometimes it shuts down randomly at about 50% battery for an hour or so then restarts just fine. I also dropped it recently and the white bit at the top of the screen shattered again...

Anyway, I'd like to buy a new phone and I'd like to buy a second hand one, for environmental and financial reasons. However, I'm worried about getting ripped off or it not performing very well because it's old (e.g. battery life). I'd like if possible to get an iPhone 4S again, because I'm used to it. (Have considered a dumbphone but the maps and photos and things are too useful for work.) I've had a quick glance on eBay and they go for very reasonable prices (£60-£70), but that seems somewhat suspicious...

What do I need to look out for in a listing? What is it reasonable to expect from a second-hand smartphone? What questions should I be asking the seller? Are there any definite no-nos?

ETA: And any advice on what to do with my old one?

[alsoknownasDean]

Obviously something to prove that it hasn't been stolen.

Anything iCloud locked, stay the hell away from it.

Check as to whether any iPhones are carrier locked. Will the same one work on all networks in the UK, or is it like the US?

Also consider going for a 5 or later for that additional future proofing. The 4S might be cheap but it's over four years old and unlikely to get the next iOS update. If £60-£70 is really all you want to spend, maybe look at an Android phone, you'll get more for your money in the secondhand market.

[shelivesthedream]

How can I tell it hasn't been stolen?!

[hyla]

On ebay, pay attention to seller ratings as well as the item description.  A phone described as 7/10 from a reputable seller with good feedback might be in better condition that a phone described as mint by a seller with few feedbacks or many negative feedbacks.  I have bought several phones from ebay, typically described as being in 7/10 or 8/10 condition (fully functioning, but with cosmetic wear such as moderate scratches), purchased from large sellers with hundreds or thousands of feedbacks and a good (>99.8%) percent of positive reviews.  All of the phones arrived in better shape than I expected from the description and have been reliable as far as battery life and operation. 

Make sure the phone is described as unlocked and able to run on your preferred network. 

Ebay does have a money back guarantee if a purchased item is not as described, so if you do end up with a stolen phone described as clean (unlikely) you won't be stuck with it.