Strut changes cause the need for alignment jobs but struts in themselves can't mess your tires up unless the springs are broken or something. The recession has caused some of these shops to work customers harder. One that I trusted serviced a locking hub on my car. As I paid for the job they told me how well they had re-greased it as per my instructions and how they had replaced the gaskets using the ones I gave them from a dealership. When I got home the hub wouldn't lock. I took it apart to find that they hadn't greased anything and they threw away the gaskets I gave them and used the old ones
You can change the struts yourself. Your local chain auto shop will lend you spring compressors. Just be aware of the incredible force those springs exert before you release the compressors. But don't do the job unless the car dives over bumps