N73 for £99.99 PAYG
Seems like a pretty good deal to me even if the N73 is an old model superceeded by far more capable (and far more expensive) models such as the N95 and N82.
Downside? Well it's PAYG not SIM-free - it might need to be unlocked if you don't want to use it on T-Mobile. Oh, and this is the price at Currys (and anyone in the UK will know this is a retailer that one tries to avoid whenever possible!)
If you're in the market for a cheap and capable smartphone, 'gerrymoth' has pointed out the Nokia 6120 Classic is available for £99.99 too (again on PAYG). That's better in many ways to the N73 but has a smaller screen. Oh and that's available from Three's website