I've got a pair of Lidls finest winter bib tights and can't really complain for the money. Just cycled through a second winter with them and I reckon there is at least another one in them - all for just £15?
It's just dependent on when they next have them in. And the sizing is ridiculous - bought an L (I'm usually an L/XL depending on brand) and they were miles too big, I had to take them back and swap them for a M.
Decathlon also do some good stuff - the 500 and 700 series stuff is great value for money.