try smiley's (smileys.com)
they have cerrvinia calzeterria sock yarn at $3 a ball (2 to 3 balls needed for a pair of socks (medium sock 2/large socks, (tall or wide) 3 balls.
still, its under $10 for sock yarn
70%superwash wool/30%nylon, lots of solid colors.
or look for Paton's Kroy sock yarn.. it too comes in wide range of solid colors, and its under $10 for enough yarn for a pair of socks.
kroy is a bit thinner, the calzetteria is a bit thicker (you can use size 2 needles)