In Catan, should you try to exclude others players from one resource?
It's not a bad strategy, if (1) you still have access to all resources, and (2) you have a group willing to trade. But it's not generally a "good strategy."

I've seen a situation where one person had a lock on all the wood (random setup). The result? everyone else went for ports, and no one traded with them.

You can't really compel competent players to pay more than 3:1 for any resource, since a port allows 3:1, and they who get too greedy tend to lose out on everything else as no one will trade with them. 

If, however, you have it on good numbers (5,6,8,9), and trade it to others at 2:1 and/or can get the 2:1 port for that resource, build your cities on it, and use it for just about everything, it's workable. A lot depends upon the group being played with.