I will go along with Frank on this one. Cutting with a glass shows up every wobble and imperfection, however when looked at with normal 20/20 everything looks great.
I have had mine for quite awhile, it is x3 I think (maybe X5), glass with a ring fluro tube. It cost me just over $100 as I purchased it from the Blind Association shop (Now Visabilty.)
As Jerry pointed out, I have mine mounted on a separate bench, that is at right angles to my saw so that it does not vibrate.
I find it difficult to use with my readers on as I have to stand to far away from the lens, so I use it without glasses or with a pair of very low powered safety glasses i have