ASDA used to sell these fantastic lycra cotton socks with a reinforced heel and toe, they were truly hard-wearing and so comfy. Then one day they just stopped stocking them. But whatever, one less reason to shop at Wal-Mart.
Marks & Spencers have good socks, if you can handle the embarrassment of setting foot on the premises in the first place. ;-) I haven't put my toe through a pair yet. Buying cheap socks really is false economy when you consider how much longer a really decent pair will last.
As long as you're putting them on your feet, that is.