I fought this as well. I had the tires balanced at Discount Tire, had the alignment done at a local shop that I have used for 25 years and had the left front CV axle replaced (this was the recommendation from the alignment shop).
Drove it with minimal improvement for a week. It would shake the steering wheel left to right pretty good at speeds between 45-55mph. I took it back to the alignment guys for a double check. They asked where I had the tires balanced at and I told them. They gave me a funny look. They told me it was the tires out of balance. They offered to balance them there. That was it! All of the tires were out of balance by at least an ounce a piece! They explained that the big box stores can't take the time to pull the old weights off before they balance the tires. They will just add weights to balance it out as best as they can. The small shops make the time to pull all of the weights first and start clean. Lesson learned.
So, from now on, I'm taking my X to my small shop for balance and rotate. Twice a year will cost $80. That's cheap to me if the car rolls smooth and the tires last longer!
