This deal from O2’s online store pips the likes of Tesco and Phones 4u by £10-20. You can get the Sony Ericsson X10 Mini Pro on O2 PAYG for £120.
O2 has a range of different PAYG tariffs, including Simplicity which offers unlimited texts for £7.50 per month.
The credit card-sized Sony Ericsson Xperia X10 Mini Pro runs Eclair (Android 2.1), with a 2.55in screen, 5MP camera and slide-out keyboard. Check out our full specs page.
(Thanks to Nicolas on HUKD)