There's some common trends that I tend to see regarding component shortages - namely, copper wire doesn't drop often enough.
That out of the way, here's what I've seen so far:
Lots of people seem to feel a squeeze from upgrading a lot of their compound structures - the most common resources I see people complaining about are nails and car batteries. This is usually alleviated around the time people start expanding into the warehouse-rich areas of the game, and become almost negligible by the time you get access to the docks.
Weapon/gear benches require treated wood and hardened metal as components. Hardened metal isn't too hard to come by, but it's a tad uncommon - only certain items of certain quality can give it. Hardened wood, however, is substantially more difficult for one reason alone - most end game items can't salvage it as a resource when recycled, meaning you have to run earlier areas of the game repeatedly.
On a personal note, my personal bane has been rope. It took me FOREVER to get enough to upgrade one of my water towers to max, and I'm still at 10/15 for the other's final level. I lost track of the number of warehouse missions I've run.
How have your experiences been?