Parts that wear slowly can creep up on an owner--you get so used to how it rides at the time you sometimes are not aware of the degradation. However - Volvo struts tend to last a very long time - and front end shops like to sell parts/jobs. You can do some tests of your own. Is there wetness on the strut housing indicating loss of shock fluid? Lift the rubber "accordian" sleeve (you may have to jack up the front to allow the springs to stretch) to get a good look. Does the car pass the "bounce" test? Push down on each front fender or step hard on the bumper (if you are a small person you may need a larger friend to assist with this test) to see how the struts react. Push down and the body should drop and then spring back to proper ride height - if it continues to bounce (up and then back down to normal height ok) beyond that first resettling your struts are weak. Also look to see that the strut housing and spring perch are not rusted. If it will pass those tests you will be ok just getting your alignment - at least until the need for the next one.
As far as their price goes - it is not out of line. -- Dave