Speeze Falconrock at Newegg for $9 plus shipping or SVC GC68 at SVC.com for $5.50 plus shipping is good heatsink for most overclocks. If you want absolute best air cooling you should use Thermalright SLK 800-900 but that's only if you want the absolute highest air overclock possible.
I've used 2 Speeze Falconrock. One for 1700+ Tbred B at 2.3 and Barton 2500+ at 2.2 both using EDRA+ board. Both idles around 41 C and 45-47 C load although I know it's about 10-15 C higher in reality.
I just purchased 1800+ Tbred B DLTC and I plan on pairing that with SVC GC68 and Abit NF7-S.
Unless you're trying to achieve that extra 50 mhz overclock, it's really pointless to purchase expensive heatsink. These cheap heatsink does its job fine and is relatively quiet with 80mm fan.
$40 for heatsink? LOL. I bought my 1700+ Tbred B for about that price. $40 chip doesn't need $40 heatsink.