If you want to stick with air-cooling, it would be very hard to find a better HS than the ThermalRight SLK900A or SLK900U, as well as the SLK947U. All three can be fitted with up to an 92mm fan. I use the SLK900A on my Barton 3000+, and have run it at 2340mHz with no heat-related issues. You should be able to find any of these three HSs for just under $40 if you shop around a bit.