Visit the Vodafone website - Make sure you do this through the Quidco link (www.quidco.co.uk) and select price plans, then the £10 price plan. You have an option of phones, pick of the bunch being the Sony Ericsson W595 or C510.
This does come on a 24 month contract, however, with the £90 cashback (which you should receive just in time for xmas), that's £10 p/m x 24months = £240 - £90 = £150/24months = £6.25 a month
So bottom line is, £6.25 a month for 2 years of 500 txts and 100 mins a month, including a brand new free phone
Seems a bloody good deal to me, hence the reason I bought mine last week.