The biggest problem with any cotton is getting wet, it is about as bad as being naked in a snow storm. Goodwill, Salvation Army, and Surplus stores are one choice.
If I hunt in cotton, the weather has to be favorable. I will still carry, gaiters, or chaps. The latter are available at Cabela's, Bass Pro and other suppliers of upland bird hunting clothing. They are available in light weight, med and heavy and they are water proof. Upland bird hunters frequently need to wear pants that provide added protection. None are as quiet as wool, and all are better than cotton when wet.