I just recently upgraded my system, and my old main went to my secondary. Now I have a set of stuff that I'd like to sell.
Athlon 64 X2 6400+ (dual core, 3.2Ghz)
Asus M2N32-SLi motherboard (had a wireless module, but I took it off in favor of more usb ports. The card has since been rendered useless because I didn't keep it in a static bag.)
4GB AData DDR2-800 memory
Thermalright Ultra-120 cooler (NOT the extreme model, has AM2 bracket, can supply LGA 775 bracket if needed)
It's reliable, but does not overclock at all. I've been using it as a database and web server with Linux, and it has done very well. The cooler is currently attached and uses Arctic Silver 5 thermal compound. I can potentially ship it attached, but I wouldn't advise it.
$200 for the whole set. I live in Denver, and if you live out here, or want to come out for a nice ski or nature vacation, picking it up is preferred to shipping. (I can even advise decent places to stay if you're out here on vacation. It really is a nice place to visit. I stay in state for my vacations because the area is so beautiful.)
I also have a Geforce 8800GTX if you are interested at $100. Still has all the original cooling, which has never been taken off. It also doesn't overclock at all, but is perfectly stable and reliable.