The green ones are by Scott Nichol (and come in several colours - I have the green and the rust colours). They retail for about £15 a pair.
The red ones are by Corgi (and come in blue as well as red) and retail for about £18 a pair.
So, no, they're not cheap, but they are lovely.
They are a little pricey, but they are good chunky winter socks. I wear the Scott Nichol ones often with both brogues and brogue boots.
@Sam: Loafers and socks of any kind are a difficult combination. I'd wait for the weather to warm up some and go sockless (or wear invisible socks). I really can't imagine argyle working with them. You're pairing Italian riviera chic footwear with gruff Scottish sockwear; it sounds a recipe for disaster.
And I wear red socks (with bold pink flowers on too) with suits (I tend to wear my wilder socks with suits and my earthier, nordic, fairisle socks for casual wear) and I love it. I get complimented on my sockwear often! GQ would deem these to be Super Jazz hands, I'm sure.
http://www.coggles.com/product-media...ed-Socks-1.jpg
It might be a little sad that I get so excited about socks.

