If you wanna OC then you need more than just a new CPU, you will also need a "bastard" sized cooler to handle the extra output.
However there are also Xeon processors out there, you can get i7 grade performance at the price of an i5 and all you loose is overclocking and integrated graphics.
Or you can go for an older solution and buy AMD's FX 8350. The choice is yours, but I'd say you'd want to come through as cheaply as possible.