One of my problems in finding sock yarn is that I get these particular colors in my head and then I can't find that color in sock yarn, like the deep medium pink I want for the piggy toe socks (DrLeonesse mentioned the same problem in the comments) or the rich kelly green I want for the Leaves socks in the Socks, Socks, Socks book.
I did recently purchase some of Elann's Sock it to Me Essentials. Like LaurieM mentioned in the comments, I also thought the colors weren't quite what I saw on the website - they seemed more faded in real life. Still the price is excellent so I guess I'll combine those with some of the other new sock yarns to get enough colors.
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HERE is the link to the German sock book I mentioned. Pat told me about it and that there is a possibility of an upcoming translation to English. I used Google Translate and it looks like there are a good amount of colorwork patterns.