Question: Do you actually need a new TV, or just a smart TV? If you only need the 'smart' bit, save your money and get one of these:
http://www.nowtv.com/box
It's got more apps than most smart TVs (I'm using the TuneIn app on mine, for internet radio, as I'm typing) plus the option of getting some extra TV channels cheaply (such as Gold, Sky 1, Sky Arts 1, Comedy Central, etc) without needing a satellite or cable subscription. Mine cost £16 from Asda, including 3 months access to the 'Entertainment Package'.