PC 2100 DDRAM Any Deals?

As it says above, I would like to know of any reliable company’s that offer decent prices on 512 MB of that particular amount of RAM.

I have searched Google for quite a bit, but would like your opinions of past purchases/downfalls etc. I have one site that looks like a good one but I’m not that well up on my knowledge of RAM brands. What is good and what is crap?
Is their something to look out for or is it just potluck.

Thanks for any feedback