The Athlon II X4 620 seemed decent value for money at about £75, but I hadn't heard of this before: Yoyotech - Athlon II X3 A triple-core Athlon II for £37. Presumably there is a fourth core ready to enter the unlocking lottery?
Brilliant, at such a low price, there's no need to go for the Athlon II X4. It's also around the same price as some of the Athlon II X2 series, bear in mind that this is being sold as an OEM product so most likely no included HSF.