Here you go only £4 should do the job http://www.ebuyer.com/product/86519

Looks like it comes with the heatsink aswell so you'll have to carefully take out your heatsink under the main fan, and then apply the thermal paste which comes with it to the cpu(very thin layers, use a credit card etc to spread it) you dont need much at all but you need to put some on.

P.s you will need so cpu cleaner to clean off the off thermal paste before you apply the new stuff