Since I tend to be ... thrifty?
... I like to spend the least on something with quality that works. We have used these Cipa #11950 mirrors for several years, first on our quad cab Dakota, now on the RAM. They do have some vibration shake, but not so much that it is distracting or that you can't see what is 'out there'. As long as the trailer is not a full 8' width, these work really well, can be easily adjusted and removed, are inexpensive and the straps are replaceable as they wear from sun and stretching.
See
http://www.amazon.com/CIPA-11950-Uni.../dp/B00029WRKA for $5.54 each. I think I paid $15 ea from the local RV dealer when I bought them 4 years ago. Just replaced the straps for $8.00 a pair, from Amazon too.