A teacher friend is leading a class summer trip abroad and wants to supply each of the pupils with a mobile phone for the duration of the trip. The school will purchase them and then reuse them in trips the following years. They want something as basic and cheap as possible - the only functions they need to have are calls and SMS (no camera etc). Anyone have any idea where the best place for them to buy 30+ unlocked phones (they will be using local SIMs abroad). THANKS!