I bought PC3200 from an Ebay vendor. TheMemoryPro, he was good. I dont remember the brand name but he had like 17,000 transactions on ebay with a 99% customer happiness rating
A side note, I don't know what system you're trying to upgrade, but assuming it only takes PC2100, I'd check what types of RAM it can handle. I don't believe my desktop can take over 1GB sticks...