What are the signs/symptoms that my Subie may be out of alignment?

Wheel pulling to one side...vibration at speeds above like 45 - 55 MPH. An alignment is only like $40 - $50.

 

Also, are your tires wearing unevenly? That was a major thing that my Legacy did when it was all out of alignment.

thanks.

I have a problem with the steering wheel jerking to the left at all speeds, but greatest around 30mph. And the steering wheel jerks to the right in reverse gear. weird stuff. the steering wheel jerks the side and rights itself and this speeds up with an increase in mph (sort alike a vibration, but slower and only to the one side). feels like something is bent or rubbing or something...I'm puzzled.