OK, bear with me on this one as I just did it myself after my old 360 RROD'd on me.
My local Tesco are offering the Xbox 360 Elite for £199 with 2 free chart games.
Tiger Woods Golf
Fight Night 4 Boxing
Personally I have no interest in those 2 games, however my local Blockbuster are also offering £45 instore credit for those 2 in trade in.
Tiger Woods is also a qualifying game for the £9.99 Chart game deal they're doing on trade in.
So, buy the Elite @ £199, trade in the 2 free games for £45 credit. You can then get Batman AA for nothing and have £8 of Blockbuster credit still on your account.