I am currently building a budget gamer and have been back and forth about the CPU heatsink/fan. at first I picked out a $23 thermetech but now am thinking about :
Newegg.com - Spire SP414S8-H 70mm Sleeve CPU Cooling Fan/Heatsink - Retail
Its $6 and has ok reviews. I am going to be using a Pentium 4 3.0 GHz CPU. the case set up I have should keep everything cool with a 90mm in the back and a 120mm in the front. My case also has the cone over the CPU in the side panel.
If you know of any good coolers let me know, I can't spend more than $20 on it however because I am on a very limited budget.
I may try and overclock if everything supports it, not sure about that yet but want to be ready.
I will be using Artic Silver 5 not the bubble gum they stick on there.