I'm 6'7, 284 pounds, it's nearly impossible to find pants in store....I buy 2xl or if lucky 2xlt for shirts in most big box stores and they seem to be fine. But yeah finding any sort of pants, be it jeans or dockers is impossible. It stopped being easy over 10 years ago....A couple of stores actually ended at my inseem (36) but stopped that.
It sounds strange but Tractor supply company actually carries Bluejeans that go to my length, and even my waist, and under 40 bucks a pair, but most stores only carry one or two pairs and they usually get snapped up right away. They get them on a Tuesday, and they're gone by Friday. I used to pass one by every time I got off the freeway from my commute, so I would stop in at least one a month just to check.
Now, for the most part, I just order online, usually from Amazon. It sucks because you can't try anything on. And then you have to send them back if they turn out not to fit...and it's not like you can walk in and walk out the same day with clothes. I by Carhart for Jeans because they do have my size, and they're not cheaply made that fall apart after a few washings, which makes them a good value. The Tractor Supply line is like Carhart in that they're pretty rugged and things like the belt loops to break after a few wearings.
One place that you may have luck at is outlet malls....Where companies like reebok, or levi's dump their merchandise. I've found sometimes 1 or 2 pairs of any given line in my size, like at a Dockers or Levis outlet.
It's frustrating...like others have said to places like, Jos A Banks, or Men's wearhouse, or Big and tall, and everything is twice as much as the same product at a department store for a "normal" sized person.