Buying a mobile phone on eBay

I was thinking of getting a new mobile phone. Is there an advantage in going to ebay for this?
The person I want the phone for is on a pay as you go phone but it is acting up a little. If I buy a phone for say €100 ( like a motorola flip thin one) is it easy to unlock and use here? Some of the phones on ebay are unlocked so are ok to use here? Can all phones be unlocked?

If the phone isn't already unlocked plug the make/model of the phone into google with the words unlock and see what you find. I bought a phone on ebay a few months ago and it is fine but needs a firmware upgrade to bluetooth with my car, apart from that it's great. I'd also advise buying a new cover as it freshens up the phone for a few euro.

To be honest, if the person is on a pay-as-you-go basis and has no contract to get out of, it might be simpler to let them use up their remaining credit and then just buy a new 'phone from their preferred network operator — they're so heavily discounted as to cost next to nothing, for a basic model, and then (s)he'd have another 12-month guarantee. If they move to a different network, they can keep their old 085, 086 or 087 number, too. Alternatively, they might be eligible for an upgrade at reduced cost, from their original operator.

There's a [broken link removed] forum over on Boards.ie which might be worth checking, if you want a cheap second-hand phone.