I found this discussion to be very helpful and thought I would relate our limited trekking pole experience in this venerable thread.
I bought my Leki Malalu Trail (or maybe it is Trail Malalu) poles for $79 at L.L. Bean last year after looking over the assortment of poles at the main store in Freeport and getting some advice from the clerk in that department. The poles have three sections and collapse to 25-1/2 inches. I would have preferred poles with cork grips but there were none available in my price range which was under $100. As it turns out the foam grips have worked just fine for me and I have had no problem even on hot days. I also decided not to spend the extra money for poles with shock absorbers so I don't know what I am missing.
Before we went to Glacier, Carlene couldn't decide if she wanted poles or not. Once we were in West Glacier, the thought of hiking Apgar Lookout, and the Sperry and Gunsight Pass trails got to her and she decided she wanted poles. Our friends in Whitefish recommended the Glacier Outdoor Center at West Glacier as a good place to buy or rent poles and that was a good choice:
http://www.glacierraftco.com
Carlene considered renting poles but decided to buy some Like-Link Teton Backcountry poles for $49. They have two sections, foam grips, no shock absorbers and collapse to 30-1/2 inches.
We have been quite pleased with both sets of poles.
Two points of advice:
1. If you are ready to start a hike and need to (1) adjust your poles and (2) apply sunscreen, do it in that order. I did it in the reverse order once and found the locking mechanism would slip because I got some sunscreen on the poles. Once I realized this and carefully wiped the sunscreen residue off the poles, the locking mechanism worked fine. Aside from the sunscreen problem, we have had no problem with the twist and lock mechanism.
2. For some reason there is an exceptionally strong bond between the "removable" rubber tips on the Life-Link poles and the tip of the pole itself. Have these rubber tips removed at the store if possible. We found it was very difficult to remove these even after they have been taken off and on several times. I didn't have this problem with the Leki poles.
I also spoke with one experienced hiker at Sperry Chalet who was very pleased with inexpensive poles he had obtained at Walmart. He was a metalurgist by profession and told me that he had studied the metal used in these poles and found that it was very durable and of good quality.
Thanks again for all of the advice on this thread and our poles greatly enhanced our hiking pleasure in Glacier last year.
Lyman