FrostyTech have tested a heatsink from Evercool, a company not normally known for producing heatsinks that run this cool... should be a pretty cheap model to pick up by the looks of it too.
"The Evercool Buffalo HPFA-10025 is a lower-noise AMD Athlon64 heatsink for socket 754, 939, 940 and AM2 processors. A fan resembling the kind used with the Arctic Cooling Freezer 64 Pro heatsink is employed to move air relatively quietly through the aluminum fins. The Buffalo's fan rotates at a fixed speed of 1800RPM, and is supported from the aluminum fins by four hidden rubber pads.
The CPU mounting clip uses one, or all three prongs on the two different styles of AMD heatsink retention frames in use. Clamping pressure is applied by a small cam at one end, and the clip installs without the use of any tools whatsoever."