Buying 2nd Hand iPhone Off Adverts.ie

[galwayman]

Hi.
I have recently broken my iPhone 4 and have been told that it is beyond repair. I didn't insure it & am looking to get a replacement.
I am under contract with three for another year or so.

I have seen some for around €300 on adverts.ie & donedeal.ie etc.

I'm just wondering - what can I do to be more sure that I will not be victim of any type of scam when purchasing an iPhone in this manner?
If I buy an iPhone that is supposedly locked to the three network, will it work straight away when I put my own SIM card into it?
I'm not too savvy when it comes to smartphones but I seem to remember that my initial iPhone only worked after I had synched it through iTunes.

I am just really wondering what I can do to check that the phone is legit bearing in mind that I am not really that well up on phones etc. I can't afford to shell out €600+ for a new phone but could stretch to €300.

Thanks

[Minder]

I dunno how it works in the south but since you only have it a year I would take it to the Apple shop, you could probably get a new/refurb one for £120.

[Sky Blue Gael]

I broke mine before (water damage). Had no insurance and wasn't covered by warranty. Took to the apple store and they replaced it free of charge. They said some people get a one off free replacement. Think it's at random. Would be well worth a shout