In reply to KingStapo:
My experience of cycling gear is this:
1) Buy the cheapest shit possible, because I'm a cheapskate.
2) It falls apart in a few months
3) Buy the medium quality stuff.
4) It doesn't fall apart, but when cycling in 'difficult' conditions it leaks/chafes/sweats/gets cold etc
5) Buy the expensive stuff
6) Enjoy, comfortable, misery-free* cycling in all conditions, at the expense of having had to buy the same item three times.
Moral of the story - if you want water resistant, breathable, comfortable cycling gear, it is cheaper to buy expensive first.
Personally, for a set of winter bib-tights, I wouldn't even bother looking at anything that cost less than 80 quid. But, of course, it depends on how comfortable you want/need to be. 40 quid puts you in between cheap and medium.
*no guarantees!