Yes, but in your case, the only real valuable items you presented were the Defias Boots and Defias Belt. And that's mainly value aimed towards collectors since they aren't valid competitors for any BiS spots atm. But who knows how the future looks like. They're GF'd and that makes them desirable to certain individuals, and that's where their value come in.
Foreman's is not GF'd and have exact same stats as an easier obtainable green item, therefore they don't really have any significant value other than "just to have them". Again, this item is not a BiS contender of any sort.
If I were to price the items based on what I've seen, I would place Defias Belt at around 300k, and Defias Boots around 400-500k. Foreman's is really a hit or miss. Personally I wouldn't pay a dime over 20k. That's just me though.
Everything else you listed is easily farmed, especially the Defias gloves and legs. Idk if the thread is still lying around on this site, but there was a thread a good while back that went into detail about just how easy they are to farm.
You need 2 things.
1) A hunter that has trap + feign death.
2) A lvl 19 leather wearer with stealt, druid/rogue.
Then you freezing trap one of the defias mobs, kill the other while the lvl 19 sits in stealth. You then use feign death and the mob will reset. Rinse and repeat until you get your desired drop(s).