I can't find any ram for my mobo!

Let me elaborate. Here's what I bought back in early 2004:

AMD Athlon64 FX-53 (Socket 940)
ASUS SK8V (VIA K8T800)
Corsair XMS 1GB (2x512MB) PC-3200 ECC Reg. (TWINX1024RE-3200LLPT)

Here is where I run into a problem. I didn't know enough about CAS latency that I purchased this a couple months ago:

Crucial 1GB (2x512MB) PC-3200 ECC Registered (CT2KIT6472Y40B) CL-3

I ran a test in EVEREST to find a temp sensor and happened to notice that my memory was running at PC-2100. That's when I remembered I had read somewhere that the RAM speed is determined by the weakest link. So I pretty much screwed myself. My read/write speed skyrocketed after removing the Crucial RAM.

It's been so damn long that I'm having trouble finding some DDR400 ECC Reg. low latency sticks. I've searched and searched, but I can't seem to find anything. I came across one that was $500, but that was ridiculous considering I paid $300 for the first set over 5 years ago.

Basically, I need to find some paired RAM and apparently I can't do it by myself. I was hoping someone here might know something I don't. I really don't want to sacrifice my low latency, but 1GB is becoming insufficient quickly. Anyone?