Pants will wear out. I wear Carhardt washed twill pants every day. They hold up really well for heavy jobs, but won't last forever. I have several pairs that are ratty and reserved for extra dirty work. At most, they last me 2 years before they look like hobo pants.
I don't like the cut of dickies, and they aren't as tough as the carhardt washed twills.
The washed twills are $35-50 US.
Beyond these pants, everything else is a trade-off. Better pants, kuhl, 5.11, Deluth, heavy duty Carhardt Duck; all more expensive, some to a laughable extent.