I have a Nokia 100 which is great, Primitive but did the job and battery life is about 2 weeks between charges. £10 from Asda but they then bashed them out for £5.
I went off for a punt once (and was likely running late) and it wouldn't unlock so I went and got a Nokia 106 (£16) - then the original unlocked when I got to my car. Anyway 106 - bad phone. It has a colour screen, basic camera and you can add a microSD which is nice to store pics of various girls spesh for a plan B. The BIG problem with it is the keypad lock. I can set them to lock after 1 minute inactivity and the 100 works perfect. The 106 doesn't auto lock in a few of the screens. I'm single so not a massive problem there but I like the peace of mind that nobody could just pick my phone up and find it unlocked, lots of girls numbers, pics, texts on it.