I believe I've posted before about the dearth of inexpensive over-the-calf dress socks, especially in colors other than solid black, navy, or dark brown.
I recently ordered a pair of scarlet red socks for Christmas from Viccel, a fairly new sock company in Turkey. With this link for 20% off, courtesy of the Off the Cuff D.C. blog, they came to just under $10; at first glance, that still seems kind of expensive for one pair of socks, but it's really not considering that they're over-the-calf, 100% cotton, and sized (as opposed to the usual one-size-fits-none), and that the price includes shipping from Turkey.
They have plenty of other unusual colors too; hopefully they'll eventually add some patterns.
I'll report back with my verdict after I get them.