Nokia 1661 is for £0.99 at e2save. You have to buy talktime for £10.00 (Talkmobile network).
The offer is
here.
The phone is basic one, may be useful as spare one.
Cash back site Quidco is offering £7.50 cashback on this deal. Though there's no 100% guarantee of the such cashbacks, there are high possibility of getting for this deal as they are reliable (Quidco and e2save).
So possibly you might get above deal - phone + talktime of £10.00 for £3.49
Nokia 1661 details :
The Nokia 1661 mobile phone is reliable, practical and easy to use with a respectable price tag that won't break the bank! Featuring a powerful 3-in-1 speaker for louder ringtones for hearing your calls in noisy environments and enjoying a clearer handsfree function. Tune into your favourite radio stations with the integrated FM radio, even find those lost keys with the built in torch.
Customise your sound with downloadable polyphonic ringtones and hold an impressive 500 phonebook contacts on your Nokia 1661. This is an ideal choice for you if you are looking for a mobile phone that you can make calls and send texts easily and navigate around menus quickly and effortlessly.
•Don't struggle hearing your phone with the powerful 3-in-1 speaker
•Listen in to your favourite stations with FM Radio
•Never lose your keys again with a handy built-in torch
•Store up to an impressive 500 phonebook entries
•Customise your mobile phone with downloadable polyphonic ringtones
•Freedom to move with the built in handsfree function 
