there are many cheap graphic cards and CPUs, just look at HD4870, HD4890, HD4850, the whole nvidia 8800 serie, nvidia GTX 2** serie and many more.
as for CPUs, just have a look at wolfdale or conroe.
nowadays you can find all this stuff at a very cheap price, if you are overclocking for fun (just like i do) doesn't matter if you have the latest 500 € GFX or you are using a second hand 50€ 8800 GTX.