Aftermarket cooling for HD 4870

I would like to spend $50 or less and either get an aftermarket cooler for my HD4870 or just get a 10%+ more powerful video card that is also quieter at the same time.

I don't figure that last one is going to happen, but if it can that would obviously be the preferable option.

I am confident working with computer hardware, but I haven't dismantled a video card before.

Anyway ease of install is a concern as is price.

I was looking at some Arctic stuff, but I figured I would ask the experts here about which brands and models to trust since one is as good as another to me.