I will let Mark handle the questions about our Klipsch products. However, I will share some experience from using other headphones. Like you, tidmack, I try to take good care of my headphones. I try to buy the carrying cases, wrap the cables correctly, etc.
I had some Sony "in-ear" headphones while in college. These were the ones which had soft tips like in-ear monitors, but they didn't really seal, and they weren't "pro style" (over the ear). I got about 2 years out of these before I think one of the micro-speakers blew out (lots of distortion, etc). At that time I paid about $50. I got a set of Shure E2c's about 2 years ago (for free, it was nice). Those are $100 retail. Aside from losing an eartip on a plane, I have had no problem with these. Like you, I use them to mow the yard, etc. Now that I travel for work, I have given them even more use. I'd bet I could get at least 2 years more out of them.
When you compare these two models, the Shure ones use a thicker cable. I'd say it has about twice the diameter of the Sony ones. Also, the strain relief on the Shure ones is much improved. The strain relief (or lack thereof) is probably an important factor to consider as well. Most cheap ones will use some little rubber piece attached at the end which clamps to the cable. Since the E2c's are clear, you can actually see they have some strain relief on the cable on the inside of the shell, as well as a higher-quality rubber piece on the outside. Of course, you would also conclude that Shure would know how to make their headphones though because of all the touring acts that use them. So, they have a lot of test data to support "rough" use.
There is another component that I cannot speak to. That would be the fact that I have always owned micro-speaker models (because I'm cheap). Even the free E2c's are micro-speakers. The balanced armature drivers in all of the Klipsch products are completely different in operation from a "normal" transducer. Based on my engineering instincts I would suspect that the armatures don't have to work as hard and would probably last longer than any micro-speaker, including higher-quality ones like the E2c. However, I reserve the right for Mark to tell me how wrong I am.
So, based on my own observations, craftsmanship (and thus price) does make a difference in durability.