I own two pairs of Decathlon hiking trousers, bought just over a year ago. They are really great, hard wearing, easy to wash, not baggy, not stretchy, quick to dry and they fit me perfectly. They were £7.99 each. When I hiked up to the top of Great Gable recently in the cold, I just wore my long johns underneath, no problems at all, my legs were as warm as toast.
My most expensive pair of hiking trousers were from Marmot, £70 but they are nowhere as good as my Decathlon's.
I'm sure they are not on sale now but bear with me. I'll have a look on the site and report back to you.