Used Android Phone Recommendation?

Hey guys, I'm not really much of an Android follower, so I'd appreciate some thoughts and advice.

Fairly recently my wife dropped her Galaxy S2 in the bath 6 months into her 24 month contract (sigh) and the result was fairly unsurprising. I managed to get £150 selling it as spares/repairs eBay, but now I'm looking to get her a replacement (used) phone.

However, looking on eBay, the average selling price of a replacement Galaxy S2 seems to be high considering the phone's age, and I'm assuming that's down to consumer awareness and demand. So here's my thinking: there must be phones that are on par with an S2 but have less consumer awareness/demand than an S2, resulting in a lower price, or more recent model for my money.

As an example, the Xperia S seems to be going for around the same price as an S2, while having many better specs.

So, do you guys know of any other phones that are lesser known, but on par with an S2 for me to look into? I'm in the UK, so the phones will have to be GSM.

Perhaps this will be an exercise in futility, or perhaps I'll be able to get my wife a slight upgrade for the extra cash we need to spend to get her away from my old painfully slow iPhone 3G.

Thanks