I've sent a restock of my plastic confederates to Classic Toy Soldiers.
Classic Toy Soldiers was my first introduction to buying toy soldiers online. I remember browsing through their catalog, picking out which of their recast sets of Marx I needed first. I was in college, unmarried, working, and had plenty of disposable income. The core of my collection was acquired during those good old days through the folks at CTS.
Also, if you're looking to introduce someone, maybe a kid, into the hobby, I would recommend their pre-made playsets. Good value, and top quality.